UTF-8 encode and decode: Difference between revisions

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π„ž U+1D11E F0 9D 84 9E
π„ž U+1D11E F0 9D 84 9E
</pre>
</pre>

=={{header|BaCon}}==
BaCon supports UTF8 natively.
<lang bacon>DECLARE x TYPE STRING

CONST letter$ = "A ΓΆ Π– € π„ž"

PRINT "Char", TAB$(1), "Unicode", TAB$(2), "UTF-8 (hex)"
PRINT "-----------------------------------"

FOR x IN letter$
PRINT x, TAB$(1), "U+", HEX$(UCS(x)), TAB$(2), COIL$(LEN(x), HEX$(x[_-1] & 255))
NEXT</lang>
{{out}}
<pre>Char Unicode UTF-8 (hex)
-----------------------------------
A U+41 41
ΓΆ U+F6 C3 B6
Π– U+416 D0 96
€ U+20AC E2 82 AC
π„ž U+1D11E F0 9D 84 9E</pre>


=={{header|C}}==
=={{header|C}}==

Revision as of 17:37, 20 August 2020

Task
UTF-8 encode and decode
You are encouraged to solve this task according to the task description, using any language you may know.

As described in UTF-8 and in Wikipedia, UTF-8 is a popular encoding of (multi-byte) Unicode code-points into eight-bit octets.

The goal of this task is to write a encoder that takes a unicode code-point (an integer representing a unicode character) and returns a sequence of 1-4 bytes representing that character in the UTF-8 encoding.

Then you have to write the corresponding decoder that takes a sequence of 1-4 UTF-8 encoded bytes and return the corresponding unicode character.

Demonstrate the functionality of your encoder and decoder on the following five characters: 

Character   Name                                  Unicode    UTF-8 encoding (hex)
---------------------------------------------------------------------------------
A           LATIN CAPITAL LETTER A                U+0041     41
ΓΆ           LATIN SMALL LETTER O WITH DIAERESIS   U+00F6     C3 B6
Π–           CYRILLIC CAPITAL LETTER ZHE           U+0416     D0 96
€           EURO SIGN                             U+20AC     E2 82 AC
π„ž           MUSICAL SYMBOL G CLEF                 U+1D11E    F0 9D 84 9E

Provided below is a reference implementation in Common Lisp.

8th

<lang 8th> hex \ so bytes print nicely

[ 

 "\u0041", 
 "\u00F6",
 "\u0416",
 "\u20AC"

] \ add the 0x1D11E one; the '\u' string notation requires four hex digits 

 "" 1D11E s:+ a:push

\ for each test, print it out and its bytes: ( 

 dup . space
 b:new 
 ( . space drop ) b:each 
 cr

) a:each! drop

cr \ now the inverse: [ 

 [41],
 [C3,B6],
 [D0,96],
 [E2,82,AC],
 [$F0,9D,84,9E]

]

( 

 dup . space
 b:new >s  .  cr

) a:each! drop

bye </lang>

Output:

A 41 
ΓΆ c3 b6 
Π– d0 96 
€ e2 82 ac 
π„ž f0 9d 84 9e 

[41] A
[c3,b6] ΓΆ
[d0,96] Π–
[e2,82,ac] €
[f0,9d,84,9e] π„ž

Ada

Works with: Ada version 2012

<lang Ada>with Ada.Strings.Fixed; use Ada.Strings.Fixed; with Ada.Strings.UTF_Encoding.Wide_Wide_Strings; with Ada.Integer_Text_IO; with Ada.Text_IO; with Ada.Wide_Wide_Text_IO;

procedure UTF8_Encode_And_Decode is 

  package TIO renames Ada.Text_IO;
  package WWTIO renames Ada.Wide_Wide_Text_IO;
  package WWS renames Ada.Strings.UTF_Encoding.Wide_Wide_Strings;

  function To_Hex
    (i : in Integer;
     width : in Natural := 0;
     fill : in Character := '0') return String
  is
     holder : String(1 .. 20);
  begin
     Ada.Integer_Text_IO.Put(holder, i, 16);
     declare
        hex : constant String := holder(Index(holder, "#")+1 .. holder'Last-1);
        filled : String := Natural'Max(width, hex'Length) * fill;
     begin
        filled(filled'Last - hex'Length + 1 .. filled'Last) := hex;
        return filled;
     end;
  end To_Hex;

  input : constant Wide_Wide_String := "AΓΆΠ–β‚¬π„ž";

begin 

  TIO.Put_Line("Character   Unicode    UTF-8 encoding (hex)");
  TIO.Put_Line(43 * '-');
  for WWC of input loop
     WWTIO.Put(WWC & "           ");
     declare
        filled : String := 11 * ' ';
        unicode : constant String := "U+" & To_Hex(Wide_Wide_Character'Pos(WWC), width => 4);
        utf8_string : constant String := WWS.Encode((1 => WWC));
     begin
        filled(filled'First .. filled'First + unicode'Length - 1) := unicode;
        TIO.Put(filled);
        for C of utf8_string loop
           TIO.Put(To_Hex(Character'Pos(C)) & " ");
        end loop;
        TIO.New_Line;
     end;
  end loop;

end UTF8_Encode_And_Decode;</lang>

Output:
Character   Unicode    UTF-8 encoding (hex)
-------------------------------------------
A           U+0041     41 
ΓΆ           U+00F6     C3 B6 
Π–           U+0416     D0 96 
€           U+20AC     E2 82 AC 
π„ž           U+1D11E    F0 9D 84 9E

BaCon

BaCon supports UTF8 natively. <lang bacon>DECLARE x TYPE STRING

CONST letter$ = "A ΓΆ Π– € π„ž"

PRINT "Char", TAB$(1), "Unicode", TAB$(2), "UTF-8 (hex)" PRINT "-----------------------------------"

FOR x IN letter$ PRINT x, TAB$(1), "U+", HEX$(UCS(x)), TAB$(2), COIL$(LEN(x), HEX$(x[_-1] & 255)) NEXT</lang>

Output:
Char    Unicode         UTF-8 (hex)
-----------------------------------
A       U+41            41
ΓΆ       U+F6            C3 B6
Π–       U+416           D0 96
€       U+20AC          E2 82 AC
π„ž       U+1D11E         F0 9D 84 9E

C

<lang C>

  1. include <stdio.h>
  2. include <stdlib.h>
  3. include <inttypes.h>

typedef struct { char mask; /* char data will be bitwise AND with this */ char lead; /* start bytes of current char in utf-8 encoded character */ uint32_t beg; /* beginning of codepoint range */ uint32_t end; /* end of codepoint range */ int bits_stored; /* the number of bits from the codepoint that fits in char */ }utf_t;

utf_t * utf[] = { /* mask lead beg end bits */ [0] = &(utf_t){0b00111111, 0b10000000, 0, 0, 6 }, [1] = &(utf_t){0b01111111, 0b00000000, 0000, 0177, 7 }, [2] = &(utf_t){0b00011111, 0b11000000, 0200, 03777, 5 }, [3] = &(utf_t){0b00001111, 0b11100000, 04000, 0177777, 4 }, [4] = &(utf_t){0b00000111, 0b11110000, 0200000, 04177777, 3 }, &(utf_t){0}, };

/* All lengths are in bytes */ int codepoint_len(const uint32_t cp); /* len of associated utf-8 char */ int utf8_len(const char ch); /* len of utf-8 encoded char */

char *to_utf8(const uint32_t cp); uint32_t to_cp(const char chr[4]);

int codepoint_len(const uint32_t cp) { int len = 0; for(utf_t **u = utf; *u; ++u) { if((cp >= (*u)->beg) && (cp <= (*u)->end)) { break; } ++len; } if(len > 4) /* Out of bounds */ exit(1);

return len; }

int utf8_len(const char ch) { int len = 0; for(utf_t **u = utf; *u; ++u) { if((ch & ~(*u)->mask) == (*u)->lead) { break; } ++len; } if(len > 4) { /* Malformed leading byte */ exit(1); } return len; }

char *to_utf8(const uint32_t cp) { static char ret[5]; const int bytes = codepoint_len(cp);

int shift = utf[0]->bits_stored * (bytes - 1); ret[0] = (cp >> shift & utf[bytes]->mask) | utf[bytes]->lead; shift -= utf[0]->bits_stored; for(int i = 1; i < bytes; ++i) { ret[i] = (cp >> shift & utf[0]->mask) | utf[0]->lead; shift -= utf[0]->bits_stored; } ret[bytes] = '\0'; return ret; }

uint32_t to_cp(const char chr[4]) { int bytes = utf8_len(*chr); int shift = utf[0]->bits_stored * (bytes - 1); uint32_t codep = (*chr++ & utf[bytes]->mask) << shift;

for(int i = 1; i < bytes; ++i, ++chr) { shift -= utf[0]->bits_stored; codep |= ((char)*chr & utf[0]->mask) << shift; }

return codep; }

int main(void) { const uint32_t *in, input[] = {0x0041, 0x00f6, 0x0416, 0x20ac, 0x1d11e, 0x0};

printf("Character Unicode UTF-8 encoding (hex)\n"); printf("----------------------------------------\n");

char *utf8; uint32_t codepoint; for(in = input; *in; ++in) { utf8 = to_utf8(*in); codepoint = to_cp(utf8); printf("%s U+%-7.4x", utf8, codepoint);

for(int i = 0; utf8[i] && i < 4; ++i) { printf("%hhx ", utf8[i]); } printf("\n"); } return 0; } </lang> Output <lang> Character Unicode UTF-8 encoding (hex)

A U+0041 41 ΓΆ U+00f6 c3 b6 Π– U+0416 d0 96 € U+20ac e2 82 ac π„ž U+1d11e f0 9d 84 9e

</lang>

Common Lisp

Helper functions

<lang lisp> (defun ascii-byte-p (octet) 

 "Return t if octet is a single-byte 7-bit ASCII char.
 The most significant bit is 0, so the allowed pattern is 0xxx xxxx."
 (assert (typep octet 'integer))
 (assert (<= (integer-length octet) 8))
 (let ((bitmask  #b10000000)
       (template #b00000000))
   ;; bitwise and the with the bitmask #b11000000 to extract the first two bits.
   ;; check if the first two bits are equal to the template #b10000000.
   (= (logand bitmask octet) template)))

(defun multi-byte-p (octet) 

 "Return t if octet is a part of a multi-byte UTF-8 sequence.
 The multibyte pattern is 1xxx xxxx. A multi-byte can be either a lead byte or a trail byte."
 (assert (typep octet 'integer))
 (assert (<= (integer-length octet) 8))
 (let ((bitmask  #b10000000)
       (template #b10000000))
   ;; bitwise and the with the bitmask #b11000000 to extract the first two bits.
   ;; check if the first two bits are equal to the template #b10000000.
   (= (logand bitmask octet) template)))

(defun lead-byte-p (octet) 

 "Return t if octet is one of the leading bytes of an UTF-8 sequence, nil otherwise.
 Allowed leading byte patterns are 0xxx xxxx, 110x xxxx, 1110 xxxx and 1111 0xxx."
 (assert (typep octet 'integer))
 (assert (<= (integer-length octet) 8))
 (let ((bitmasks  (list #b10000000 #b11100000 #b11110000 #b11111000))
       (templates (list #b00000000 #b11000000 #b11100000 #b11110000)))
   (some #'(lambda (a b) (= (logand a octet) b)) bitmasks templates)))

(defun n-trail-bytes (octet) 

 "Take a leading utf-8 byte, return the number of continuation bytes 1-3."
 (assert (typep octet 'integer))
 (assert (<= (integer-length octet) 8))
 (let ((bitmasks  (list #b10000000 #b11100000 #b11110000 #b11111000))
       (templates (list #b00000000 #b11000000 #b11100000 #b11110000)))
   (loop for i from 0 to 3
      when (= (nth i templates) (logand (nth i bitmasks) octet))
      return i)))

</lang>

Encoder

<lang lisp> (defun unicode-to-utf-8 (int) 

 "Take a unicode code point, return a list of one to four UTF-8 encoded bytes (octets)."
 (assert (<= (integer-length int) 21))
 (let ((n-trail-bytes (cond ((<= #x00000 int #x00007F) 0)
                            ((<= #x00080 int #x0007FF) 1)
                            ((<= #x00800 int #x00FFFF) 2)
                            ((<= #x10000 int #x10FFFF) 3)))
       (lead-templates (list #b00000000 #b11000000 #b11100000 #b11110000))
       (trail-template #b10000000)
       ;; number of content bits in the lead byte.
       (n-lead-bits (list 7 5 4 3))
       ;; number of content bits in the trail byte.
       (n-trail-bits 6)
       ;; list to put the UTF-8 encoded bytes in.
       (byte-list nil))
   (if (= n-trail-bytes 0)
       ;; if we need 0 trail bytes, ist just an ascii single byte.
       (push int byte-list)
       (progn
         ;; if we need more than one byte, first fill the trail bytes with 6 bits each.
         (loop for i from 0 to (1- n-trail-bytes)
            do (push (+ trail-template
                        (ldb (byte n-trail-bits (* i n-trail-bits)) int))
                     byte-list))
         ;; then copy the remaining content bytes to the lead byte.
         (push (+ (nth n-trail-bytes lead-templates)
                  (ldb (byte (nth n-trail-bytes n-lead-bits) (* n-trail-bytes n-trail-bits)) int))
               byte-list)))
   ;; return the list of UTF-8 encoded bytes.
   byte-list))

</lang>

Decoder

<lang lisp> (defun utf-8-to-unicode (byte-list) 

 "Take a list of one to four utf-8 encoded bytes (octets), return a code point."
 (let ((b1 (car byte-list)))
   (cond ((ascii-byte-p b1) b1) ; if a single byte, just return it.
         ((multi-byte-p b1)
          (if (lead-byte-p b1)
              (let ((n (n-trail-bytes b1))
                    ;; Content bits we want to extract from each lead byte.
                    (lead-templates (list #b01111111 #b00011111 #b00001111 #b00000111))
                    ;; Content bits we want to extract from each trail byte.
                    (trail-template #b00111111))
                (if (= n (1- (list-length byte-list)))
                    ;; add lead byte
                    (+ (ash (logand (nth 0 byte-list) (nth n lead-templates)) (* 6 n))
                       ;; and the trail bytes
                       (loop for i from 1 to n sum
                            (ash (logand (nth i byte-list) trail-template) (* 6 (- n i)))))
                    (error "calculated number of bytes doesnt match the length of the byte list")))
              (error "first byte in the list isnt a lead byte"))))))

</lang>

The test

<lang lisp> (defun test-utf-8 () 

 "Return t if the chosen unicode points are encoded and decoded correctly."
 (let* ((unicodes-orig (list 65 246 1046 8364 119070))
        (unicodes-test (mapcar #'(lambda (x) (utf-8-to-unicode (unicode-to-utf-8 x)))
                               unicodes-orig)))
   (mapcar #'(lambda (x)
               (format t
                       "character ~A, code point: ~6x, utf-8: ~{~x ~}~%"
                       (code-char x)
                       x
                       (unicode-to-utf-8 x)))
           unicodes-orig)
   ;; return t if all are t
   (every #'= unicodes-orig unicodes-test)))

</lang>

Test output

<lang lisp> CL-USER> (test-utf-8) character A, code point: 41, utf-8: 41 character ΓΆ, code point: F6, utf-8: C3 B6 character Π–, code point: 416, utf-8: D0 96 character €, code point: 20AC, utf-8: E2 82 AC character π„ž, code point: 1D11E, utf-8: F0 9D 84 9E T </lang>

D

<lang D>import std.conv; import std.stdio;

immutable CHARS = ["A","ΓΆ","Π–","€","π„ž"];

void main() { 

   writeln("Character   Code-Point   Code-Units");
   foreach (c; CHARS) {
       auto bytes = cast(ubyte[]) c; //The raw bytes of a character can be accessed by casting
       auto unicode = cast(uint) to!dstring(c)[0]; //Convert from a UTF8 string to a UTF32 string, and cast the first character to a number
       writefln("%s              %7X   [%(%X, %)]", c, unicode, bytes);
   }

}</lang>

Output:
Character   Code-Point   Code-Units
A                   41   [41]
ΓΆ                   F6   [C3, B6]
Π–                  416   [D0, 96]
€                 20AC   [E2, 82, AC]
π„ž                1D11E   [F0, 9D, 84, 9E]

Elena

ELENA 4.x : <lang elena>import system'routines; import extensions;

extension op : String { 

   string printAsString()
   {
      console.print(self," ")
   }

   string printAsUTF8Array()
   {
       self.toByteArray().forEach:(b){ console.print(b.toString(16)," ") }
   }

   string printAsUTF32()
   {
       self.toArray().forEach:(c){ console.print("U+",c.toInt().toString(16)," ") }
   }

}

public program() { 

   "A".printAsString().printAsUTF8Array().printAsUTF32();
   console.printLine();

   "ΓΆ".printAsString().printAsUTF8Array().printAsUTF32();
   console.printLine();

   "Π–".printAsString().printAsUTF8Array().printAsUTF32();
   console.printLine();

   "€".printAsString().printAsUTF8Array().printAsUTF32();
   console.printLine();

   "π„ž".printAsString().printAsUTF8Array().printAsUTF32();
   console.printLine();

}</lang>

Output:
A 41 U+41 
ΓΆ C3 B6 U+F6 
Π– D0 96 U+416 
€ E2 82 AC U+20AC 
π„ž F0 9D 84 9E U+1D11E

F#

<lang fsharp> // Unicode character point to UTF8. Nigel Galloway: March 19th., 2018 let fN g = match List.findIndex (fun n->n>g) [0x80;0x800;0x10000;0x110000] with 

          |0->[g]
          |1->[0xc0+(g&&&0x7c0>>>6);0x80+(g&&&0x3f)]
          |2->[0xe0+(g&&&0xf000>>>12);0x80+(g&&&0xfc0>>>6);0x80+(g&&&0x3f)]
          |_->[0xf0+(g&&&0x1c0000>>>18);0x80+(g&&&0x3f000>>>12);0x80+(g&&&0xfc0>>>6);0x80+(g&&&0x3f)]

</lang>

Output:
for n in fN 0x41    do printf "%x " n -> 41
for n in fN 0xf6    do printf "%x " n -> c3 b6 
for n in fN 0x416   do printf "%x " n -> d0 96 
for n in fN 0x20ac  do printf "%x " n -> e2 82 ac 
for n in fN 0x1d11e do printf "%x " n -> f0 9d 84 9e

Forth

Forth-2012 includes the words xc!+ and xc@+ that convert code point numbers into bytes and vice versa, respectively, for the encoding the system is using. If the system uses UTF-8 (e.g., in Gforth, if it is started in a UTF-8 environment), this converts between code point number and UTF-8.

So the following code just uses these words to perform the tests.

Works with: gforth version 0.7.9_20191121
Works with: lxf version 1.6-982-823

<lang forth>: showbytes ( c-addr u -- ) 

   over + swap ?do

i c@ 3 .r loop ;

test {: xc -- :}
   xc xemit xc 6 .r xc pad xc!+ pad tuck - ( c-addr u )
   2dup showbytes drop xc@+ xc <> abort" test failed" drop cr ;

hex $41 test $f6 test $416 test $20ac test $1d11e test \ can also be written as \ 'A' test 'ΓΆ' test 'Π–' test '€' test 'π„ž' test </lang>

Output:
A    41 41
ΓΆ    F6 C3 B6
Π–   416 D0 96
€  20AC E2 82 AC
π„ž 1D11E F0 9D 84 9E

If you also want to see the implementation of xc!+ and xc@+, here it is (u8!+ is the UTF-8 implementation of xc!+, and likewise for u8@+):

<lang forth>-77 Constant UTF-8-err

$80 Constant max-single-byte

u8@+ ( u8addr -- u8addr' u )
   count  dup max-single-byte u< ?EXIT  \ special case ASCII
   dup $C2 u< IF  UTF-8-err throw  THEN  \ malformed character
   $7F and  $40 >r
   BEGIN  dup r@ and  WHILE  r@ xor

6 lshift r> 5 lshift >r >r count dup $C0 and $80 <> IF UTF-8-err throw THEN $3F and r> or 

   REPEAT  rdrop ;
u8!+ ( u u8addr -- u8addr' )
   over max-single-byte u< IF  tuck c! 1+  EXIT  THEN \ special case ASCII
   >r 0 swap  $3F
   BEGIN  2dup u>  WHILE

2/ >r dup $3F and $80 or swap 6 rshift r> 

   REPEAT  $7F xor 2* or  r>
   BEGIN   over $80 u>= WHILE  tuck c! 1+  REPEAT  nip ;

</lang>

Go

Implementation

This implementation is missing all checks for invalid data and so is not production-ready, but illustrates the basic UTF-8 encoding scheme. <lang go>package main

import ( 

   "bytes"
   "encoding/hex"
   "fmt"
   "log"
   "strings"

)

var testCases = []struct { 

   rune
   string

}{ 

   {'A', "41"},
   {'ΓΆ', "C3 B6"},
   {'Π–', "D0 96"},
   {'€', "E2 82 AC"},
   {'π„ž', "F0 9D 84 9E"},

}

func main() { 

   for _, tc := range testCases {
       // derive some things from test data
       u := fmt.Sprintf("U+%04X", tc.rune)
       b, err := hex.DecodeString(strings.Replace(tc.string, " ", "", -1))
       if err != nil {
           log.Fatal("bad test data")
       }
       // exercise encoder and decoder on test data
       e := encodeUTF8(tc.rune)
       d := decodeUTF8(b)
       // show function return values
       fmt.Printf("%c  %-7s  %X\n", d, u, e)
       // validate return values against test data
       if !bytes.Equal(e, b) {
           log.Fatal("encodeUTF8 wrong")
       }
       if d != tc.rune {
           log.Fatal("decodeUTF8 wrong")
       }
   }

}

const ( 

   // first byte of a 2-byte encoding starts 110 and carries 5 bits of data
   b2Lead = 0xC0 // 1100 0000
   b2Mask = 0x1F // 0001 1111

   // first byte of a 3-byte encoding starts 1110 and carries 4 bits of data
   b3Lead = 0xE0 // 1110 0000
   b3Mask = 0x0F // 0000 1111

   // first byte of a 4-byte encoding starts 11110 and carries 3 bits of data
   b4Lead = 0xF0 // 1111 0000
   b4Mask = 0x07 // 0000 0111

   // non-first bytes start 10 and carry 6 bits of data
   mbLead = 0x80 // 1000 0000
   mbMask = 0x3F // 0011 1111

)

func encodeUTF8(r rune) []byte { 

   switch i := uint32(r); {
   case i <= 1<<7-1: // max code point that encodes into a single byte
       return []byte{byte(r)}
   case i <= 1<<11-1: // into two bytes
       return []byte{
           b2Lead | byte(r>>6),
           mbLead | byte(r)&mbMask}
   case i <= 1<<16-1: // three
       return []byte{
           b3Lead | byte(r>>12),
           mbLead | byte(r>>6)&mbMask,
           mbLead | byte(r)&mbMask}
   default:
       return []byte{
           b4Lead | byte(r>>18),
           mbLead | byte(r>>12)&mbMask,
           mbLead | byte(r>>6)&mbMask,
           mbLead | byte(r)&mbMask}
   }

}

func decodeUTF8(b []byte) rune { 

   switch b0 := b[0]; {
   case b0 < 0x80:
       return rune(b0)
   case b0 < 0xE0:
       return rune(b0&b2Mask)<<6 |
           rune(b[1]&mbMask)
   case b0 < 0xF0:
       return rune(b0&b3Mask)<<12 |
           rune(b[1]&mbMask)<<6 |
           rune(b[2]&mbMask)
   default:
       return rune(b0&b4Mask)<<18 |
           rune(b[1]&mbMask)<<12 |
           rune(b[2]&mbMask)<<6 |
           rune(b[3]&mbMask)
   }

}</lang>

Output:
A  U+0041   41
ΓΆ  U+00F6   C3B6
Π–  U+0416   D096
€  U+20AC   E282AC
π„ž  U+1D11E  F09D849E

Library/language

<lang go>package main

import ( 

   "fmt"
   "unicode/utf8"

)

func utf8encode(codepoint rune) []byte { 

   buffer := make([]byte, 4)
   length := utf8.EncodeRune(buffer, codepoint)
   return buffer[:length]

}

func utf8decode(bytes []byte) rune { 

   result, _ := utf8.DecodeRune(bytes)
   return result

}

func main() { 

       fmt.Printf("%-7s %7s\t%s\t%s\n", "Char", "Unicode", "UTF-8 encoded", "Decoded");
   for _, codepoint := range []rune{'A', 'ΓΆ', 'Π–', '€', 'π„ž'} {
       encoded := utf8encode(codepoint)
       decoded := utf8decode(encoded)
       fmt.Printf("%-7c U+%04X\t%-12X\t%c\n", codepoint, codepoint, encoded, decoded)
   }

}</lang>

Output:
Char    Unicode	UTF-8 encoded	Decoded
A       U+0041	41          	A
ΓΆ       U+00F6	C3B6        	ΓΆ
Π–       U+0416	D096        	Π–
€       U+20AC	E282AC      	€
π„ž       U+1D11E	F09D849E    	π„ž

Alternately: <lang go>package main

import ( 

   "fmt"

)

func utf8encode(codepoint rune) []byte { 

   return []byte(string([]rune{codepoint}))

}

func utf8decode(bytes []byte) rune { 

   return []rune(string(bytes))[0]

}

func main() { 

       fmt.Printf("%-7s %7s\t%s\t%s\n", "Char", "Unicode", "UTF-8 encoded", "Decoded");
   for _, codepoint := range []rune{'A', 'ΓΆ', 'Π–', '€', 'π„ž'} {
       encoded := utf8encode(codepoint)
       decoded := utf8decode(encoded)
       fmt.Printf("%-7c U+%04X\t%-12X\t%c\n", codepoint, codepoint, encoded, decoded)
   }

}</lang>

Output:
Char    Unicode	UTF-8 encoded	Decoded
A       U+0041	41          	A
ΓΆ       U+00F6	C3B6        	ΓΆ
Π–       U+0416	D096        	Π–
€       U+20AC	E282AC      	€
π„ž       U+1D11E	F09D849E    	π„ž

Groovy

Translation of: Java

<lang groovy>import java.nio.charset.StandardCharsets

class UTF8EncodeDecode { 

   static byte[] utf8encode(int codePoint) {
       char[] characters = [codePoint]
       new String(characters, 0, 1).getBytes StandardCharsets.UTF_8
   }

   static int utf8decode(byte[] bytes) {
       new String(bytes, StandardCharsets.UTF_8).codePointAt(0)
   }

   static void main(String[] args) {
       printf "%-7s %-43s %7s\t%s\t%7s%n", "Char", "Name", "Unicode", "UTF-8 encoded", "Decoded"

       ([0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E]).each { int codePoint ->
           byte[] encoded = utf8encode codePoint
           Formatter formatter = new Formatter()
           encoded.each { byte b ->
               formatter.format "%02X ", b
           }
           String encodedHex = formatter.toString()
           int decoded = utf8decode encoded
           printf "%-7c %-43s U+%04X\t%-12s\tU+%04X%n", codePoint, Character.getName(codePoint), codePoint, encodedHex, decoded
       }
   }

}</lang>

Output:
Char    Name                                        Unicode	UTF-8 encoded	Decoded
A       LATIN CAPITAL LETTER A                      U+0041	41          	U+0041
ΓΆ       LATIN SMALL LETTER O WITH DIAERESIS         U+00F6	C3 B6       	U+00F6
Π–       CYRILLIC CAPITAL LETTER ZHE                 U+0416	D0 96       	U+0416
€       EURO SIGN                                   U+20AC	E2 82 AC    	U+20AC
π„ž      MUSICAL SYMBOL G CLEF                       U+1D11E	ED 84 9E    	U+D11E

Haskell

Example makes use of bytestring and text packages:

<lang haskell>module Main (main) where

import qualified Data.ByteString as ByteString (pack, unpack) import Data.Char (chr, ord) import Data.Foldable (for_) import Data.List (intercalate) import qualified Data.Text as Text (head, singleton) import qualified Data.Text.Encoding as Text (decodeUtf8, encodeUtf8) import Text.Printf (printf)

encodeCodepoint :: Int -> [Int] encodeCodepoint = map fromIntegral . ByteString.unpack . Text.encodeUtf8 . Text.singleton . chr

decodeToCodepoint :: [Int] -> Int decodeToCodepoint = ord . Text.head . Text.decodeUtf8 . ByteString.pack . map fromIntegral

main :: IO () main = do 

   putStrLn "Character  Unicode  UTF-8 encoding (hex)  Decoded"
   putStrLn "-------------------------------------------------"
   for_ [0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E] $ \codepoint -> do
       let values = encodeCodepoint codepoint
           codepoint' = decodeToCodepoint values
       putStrLn $ printf "%c          %-7s  %-20s  %c"
           codepoint
           (printf "U+%04X" codepoint :: String)
           (intercalate " " (map (printf "%02X") values))
           codepoint'</lang>
Output:
Character  Unicode  UTF-8 encoding (hex)  Decoded
-------------------------------------------------
A          U+0041   41                    A
ΓΆ          U+00F6   C3 B6                 ΓΆ
Π–          U+0416   D0 96                 Π–
€          U+20AC   E2 82 AC              €
π„ž          U+1D11E  F0 9D 84 9E           π„ž

J

Solution: <lang j>utf8=: 8&u: NB. converts to UTF-8 from unicode or unicode codepoint integer ucp=: 9&u: NB. converts to unicode from UTF-8 or unicode codepoint integer ucp_hex=: hfd@(3 u: ucp) NB. converts to unicode codepoint hexadecimal from UTF-8, unicode or unicode codepoint integer</lang>

Examples: <lang j> utf8 65 246 1046 8364 119070 AΓΆΠ–β‚¬π„ž 

  ucp 65 246 1046 8364 119070

AΓΆΠ–β‚¬π„ž 

  ucp 'AΓΆΠ–β‚¬π„ž'

AΓΆΠ–β‚¬π„ž 

  utf8 ucp 65 246 1046 8364 119070

AΓΆΠ–β‚¬π„ž 

  ucp_hex utf8 65 246 1046 8364 119070

00041 000f6 00416 020ac 1d11e 

  utf8@dfh ucp_hex utf8 65 246 1046 8364 119070

AΓΆΠ–β‚¬π„ž</lang>

Java

Works with: Java version 7+

<lang java>import java.nio.charset.StandardCharsets; import java.util.Formatter;

public class UTF8EncodeDecode { 

   public static byte[] utf8encode(int codepoint) {
       return new String(new int[]{codepoint}, 0, 1).getBytes(StandardCharsets.UTF_8);
   }

   public static int utf8decode(byte[] bytes) {
       return new String(bytes, StandardCharsets.UTF_8).codePointAt(0);
   }

   public static void main(String[] args) {
       System.out.printf("%-7s %-43s %7s\t%s\t%7s%n",
               "Char", "Name", "Unicode", "UTF-8 encoded", "Decoded");

       for (int codepoint : new int[]{0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E}) {
           byte[] encoded = utf8encode(codepoint);
           Formatter formatter = new Formatter();
           for (byte b : encoded) {
               formatter.format("%02X ", b);
           }
           String encodedHex = formatter.toString();
           int decoded = utf8decode(encoded);
           System.out.printf("%-7c %-43s U+%04X\t%-12s\tU+%04X%n",
                   codepoint, Character.getName(codepoint), codepoint, encodedHex, decoded);
       }
   }

}</lang>

Output:
Char    Name                                        Unicode	UTF-8 encoded	Decoded
A       LATIN CAPITAL LETTER A                      U+0041	41          	A
ΓΆ       LATIN SMALL LETTER O WITH DIAERESIS         U+00F6	C3 B6       	ΓΆ
Π–       CYRILLIC CAPITAL LETTER ZHE                 U+0416	D0 96       	Π–
€       EURO SIGN                                   U+20AC	E2 82 AC    	€
π„ž      MUSICAL SYMBOL G CLEF                       U+1D11E	F0 9D 84 9E 	π„ž

JavaScript

An implementation in ECMAScript 2015 (ES6): <lang javascript> /***************************************************************************\ |* Pure UTF-8 handling without detailed error reporting functionality. *| |***************************************************************************| |* utf8encode *| |* < String character or UInt32 code point *| |* > Uint8Array encoded_character *| |* | ErrorString *| |* *| |* utf8encode takes a string or uint32 representing a single code point *| |* as its argument and returns an array of length 1 up to 4 containing *| |* utf8 code units representing that character. *| |***************************************************************************| |* utf8decode *| |* < Unit8Array [highendbyte highmidendbyte lowmidendbyte lowendbyte] *| |* > uint32 character *| |* | ErrorString *| |* *| |* utf8decode takes an array of one to four uint8 representing utf8 code *| |* units and returns a uint32 representing that code point. *| \***************************************************************************/

const 

 utf8encode=
   n=>
     (m=>
       m<0x80
      ?Uint8Array.from(
         [ m>>0&0x7f|0x00])
      :m<0x800
      ?Uint8Array.from(
         [ m>>6&0x1f|0xc0,m>>0&0x3f|0x80])
      :m<0x10000
      ?Uint8Array.from(
         [ m>>12&0x0f|0xe0,m>>6&0x3f|0x80,m>>0&0x3f|0x80])
      :m<0x110000
      ?Uint8Array.from(
         [ m>>18&0x07|0xf0,m>>12&0x3f|0x80,m>>6&0x3f|0x80,m>>0&0x3f|0x80])
      :(()=>{throw'Invalid Unicode Code Point!'})())
     ( typeof n==='string'
      ?n.codePointAt(0)
      :n&0x1fffff),
 utf8decode=
   ([m,n,o,p])=>
     m<0x80
    ?( m&0x7f)<<0
    :0xc1<m&&m<0xe0&&n===(n&0xbf)
    ?( m&0x1f)<<6|( n&0x3f)<<0
    :( m===0xe0&&0x9f<n&&n<0xc0
     ||0xe0<m&&m<0xed&&0x7f<n&&n<0xc0
     ||m===0xed&&0x7f<n&&n<0xa0
     ||0xed<m&&m<0xf0&&0x7f<n&&n<0xc0)
   &&o===o&0xbf
    ?( m&0x0f)<<12|( n&0x3f)<<6|( o&0x3f)<<0
    :( m===0xf0&&0x8f<n&&n<0xc0
     ||m===0xf4&&0x7f<n&&n<0x90
     ||0xf0<m&&m<0xf4&&0x7f<n&&n<0xc0)
   &&o===o&0xbf&&p===p&0xbf
    ?( m&0x07)<<18|( n&0x3f)<<12|( o&0x3f)<<6|( p&0x3f)<<0
    :(()=>{throw'Invalid UTF-8 encoding!'})()

</lang> The testing inputs: <lang javascript> const 

 str=
   'AΓΆΠ–β‚¬π„ž'
,cps=
   Uint32Array.from(str,s=>s.codePointAt(0))
,cus=
   [ [ 0x41]
    ,[ 0xc3,0xb6]
    ,[ 0xd0,0x96]
    ,[ 0xe2,0x82,0xac]
    ,[ 0xf0,0x9d,0x84,0x9e]]
  .map(a=>Uint8Array.from(a))
,zip3=
   ([a,...as],[b,...bs],[c,...cs])=>
     0<as.length+bs.length+cs.length
    ?[ [ a,b,c],...zip3(as,bs,cs)]
    :[ [ a,b,c]]
,inputs=zip3(str,cps,cus);

</lang> The testing code: <lang javascript> console.log(`\ ${'Character'.padEnd(16)}\ ${'CodePoint'.padEnd(16)}\ ${'CodeUnits'.padEnd(16)}\ ${'uft8encode(ch)'.padEnd(16)}\ ${'uft8encode(cp)'.padEnd(16)}\ utf8decode(cu)`) for(let [ch,cp,cu] of inputs) 

 console.log(`\

${ch.padEnd(16)}\ ${cp.toString(0x10).padStart(8,'U+000000').padEnd(16)}\ ${`[${[...cu].map(n=>n.toString(0x10))}]`.padEnd(16)}\ ${`[${[...utf8encode(ch)].map(n=>n.toString(0x10))}]`.padEnd(16)}\ ${`[${[...utf8encode(cp)].map(n=>n.toString(0x10))}]`.padEnd(16)}\ ${utf8decode(cu).toString(0x10).padStart(8,'U+000000')}`) </lang> and finally, the output from the test: 

Character       CodePoint       CodeUnits       uft8encode(ch)  uft8encode(cp)  utf8decode(cu)
A               U+000041        [41]            [41]            [41]            U+000041
ΓΆ               U+0000f6        [c3,b6]         [c3,b6]         [c3,b6]         U+0000f6
Π–               U+000416        [d0,96]         [d0,96]         [d0,96]         U+000416
€               U+0020ac        [e2,82,ac]      [e2,82,ac]      [e2,82,ac]      U+0020ac
π„ž              U+01d11e        [f0,9d,84,9e]   [f0,9d,84,9e]   [f0,9d,84,9e]   U+01d11e

Note that the misalign there on the last line is caused by the string length of astral characters being 2 so the padding functions break.

Julia

Works with: Julia version 0.6

Julia supports by default UTF-8 encoding.

<lang julia>for t in ("A", "ΓΆ", "Π–", "€", "π„ž") 

   enc = Vector{UInt8}(t)
   dec = String(enc)
   println(dec, " β†’ ", enc)

end</lang>

Output:
A β†’ UInt8[0x41]
ΓΆ β†’ UInt8[0xc3, 0xb6]
Π– β†’ UInt8[0xd0, 0x96]
€ β†’ UInt8[0xe2, 0x82, 0xac]
π„ž β†’ UInt8[0xf0, 0x9d, 0x84, 0x9e]

Kotlin

<lang scala>// version 1.1.2

fun utf8Encode(codePoint: Int) = String(intArrayOf(codePoint), 0, 1).toByteArray(Charsets.UTF_8)

fun utf8Decode(bytes: ByteArray) = String(bytes, Charsets.UTF_8).codePointAt(0)

fun main(args: Array<String>) { 

   val codePoints = intArrayOf(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)
   println("Char  Name                                 Unicode  UTF-8         Decoded")
   for (codePoint in codePoints) {
       var n = if(codePoint <= 0xFFFF) 4 else 5 
       System.out.printf("%-${n}c  %-35s  U+%05X  ", codePoint, Character.getName(codePoint), codePoint)  
       val bytes = utf8Encode(codePoint)
       var s = ""
       for (byte in bytes) s += "%02X ".format(byte)
       val decoded = utf8Decode(bytes)
       n = if(decoded.toInt() <= 0xFFFF) 12 else 11 
       System.out.printf("%-${n}s  %c\n", s, decoded)  
   }

}</lang>

Output:
Char  Name                                 Unicode  UTF-8         Decoded
A     LATIN CAPITAL LETTER A               U+00041  41            A
ΓΆ     LATIN SMALL LETTER O WITH DIAERESIS  U+000F6  C3 B6         ΓΆ
Π–     CYRILLIC CAPITAL LETTER ZHE          U+00416  D0 96         Π–
€     EURO SIGN                            U+020AC  E2 82 AC      €
π„ž     MUSICAL SYMBOL G CLEF                U+1D11E  F0 9D 84 9E   π„ž

langur

Works with: langur version 0.8.4

<lang langur>writeln "character Unicode UTF-8 encoding (hex)"

for .cp in "AΓΆΠ–β‚¬π„ž" { 

   val .utf8 = s2b cp2s .cp
   val .cpstr = b2s .utf8
   val .utf8rep = join " ", map f $"\.b:X02;", .utf8
   writeln $"\.cpstr:-11; U+\.cp:X04:-8; \.utf8rep;"

}</lang>

Output:
character   Unicode    UTF-8 encoding (hex)
A           U+0041     41
ΓΆ           U+00F6     C3 B6
Π–           U+0416     D0 96
€           U+20AC     E2 82 AC
π„ž           U+1D11E    F0 9D 84 9E

Lingo

Since UTF-8 is Lingo's native string encoding, and UTF-8 strings can be read into byteArrays (and v.v.), such UTF-8 encoding and decoding is built-in.
Relevant Lingo functions are:
- charToNum (string): converts single-character string to unicode code point (int)
- numToChar (int): converts unicode code point (int) to single-character string
- byteArray (string): creates byte array of UTF-8 bytes for string
- byteArray.toHexString (intStart, intLen): returns hex string representation of byte array (e.g. for printing)
- byteArray.readRawString (intLen, [strCharSet="UTF-8"]): reads a fixed number of bytes as a string <lang Lingo>chars = ["A", "ΓΆ", "Π–", "€", "π„ž"] put "Character Unicode (int) UTF-8 (hex) Decoded" repeat with c in chars 

   ba = bytearray(c)
   put col(c, 12) & col(charToNum(c), 16) & col(ba.toHexString(1, ba.length), 14) & ba.readRawString(ba.length)

end repeat</lang> Helper function for table formatting <lang Lingo>on col (val, len) 

   str = string(val)
   repeat with i = str.length+1 to len
       put " " after str
   end repeat
   return str

end</lang>

Output:
Character   Unicode (int)   UTF-8 (hex)   Decoded
A           65              41            A
ΓΆ           246             c3 b6         ΓΆ
Π–           1046            d0 96         Π–
€           8364            e2 82 ac      €
π„ž           119070          f0 9d 84 9e   π„ž

Lua

Works with: Lua version 5.3

<lang Lua> -- Accept an integer representing a codepoint. -- Return the values of the individual octets. function encode (codepoint) 

 local codepoint_str = utf8.char(codepoint)
 local result = {}

 for i = 1, #codepoint_str do
   result[#result + 1] = string.unpack("B", codepoint_str, i)
 end

 return table.unpack(result)

end

-- Accept a variable number of octets. -- Return the corresponding Unicode character. function decode (...) 

 local len = select("#", ...) -- the number of octets
 local fmt = string.rep("B", len)

 return string.pack(fmt, ...)

end

-- Run the given test cases. function test_encode_decode () 

 -- "A", "ΓΆ", "Π–", "€", "π„ž"
 local tests = {tonumber("41", 16),  tonumber("f6", 16), tonumber("416", 16),
                 tonumber("20ac", 16), tonumber("1d11e", 16)}

 for i, test in ipairs(tests) do
   print("Char: ", test)
   print("Encoding: ", encode(test))
   print("Decoding: ", decode(encode(test)))
 end

end </lang>

Output:
Char: 	65
Encoding: 	65
Decoding: 	A
Char: 	246
Encoding: 	195	182
Decoding: 	ΓΆ
Char: 	1046
Encoding: 	208	150
Decoding: 	Π–
Char: 	8364
Encoding: 	226	130	172
Decoding: 	€
Char: 	119070
Encoding: 	240	157	132	158
Decoding: 	π„ž

M2000 Interpreter

<lang M2000 Interpreter> Module EncodeDecodeUTF8 { 

     a$=string$("Hello" as UTF8enc)
     Print Len(A$)=2.5   ' 2.5 words=5 bytes
     b$=string$(a$ as UTF8dec)
     Print b$
     Print Len(b$)=5 ' 5 words = 10 bytes   
     
     Print Len(string$("A" as UTF8enc))=.5  ' 1 byte
     Print Len(string$("ΓΆ" as UTF8enc))=1   ' 2 bytes
     Print Len(string$("Π–" as UTF8enc))=1   ' 2 bytes
     Print Len(string$("€" as UTF8enc))=1.5   ' 3 bytes
     Print Len(string$("π„ž" as UTF8enc))=2      '4 bytes
     a$=string$("π„ž" as UTF8enc)
     Buffer Bytes as Byte*4
     Return Bytes, 0:=a$
     \\ F0 9D 84 9E
     Hex Eval(bytes, 0), Eval(bytes, 1), Eval(bytes, 2), Eval(bytes, 3)

} EncodeDecodeUTF8 </lang>

Output:
      True
Hello
      True
      True
      True
      True
      True
      True
    0x00F0    0x009D    0x0084    0x009E

Mathematica

<lang Mathematica>utf = ToCharacterCode[ToString["AâЖ€", CharacterEncoding -> "UTF8"]] ToCharacterCode[FromCharacterCode[utf, "UTF8"]]</lang>

Output:
{65, 195, 182, 208, 150, 226, 130, 172}
{65, 246, 1046, 8364}

Perl

<lang perl>#!/usr/bin/perl use strict; use warnings; use Unicode::UCD 'charinfo'; # getting the unicode name of the character use utf8; # using non-ascii-characters in source code binmode STDOUT, ":encoding(UTF-8)"; # printing non-ascii-characters to screen

my @chars = map {ord} qw/A ΓΆ Π– € π„ž/; # @chars contains the unicode points my $print_format = '%5s  %-35s'; printf "$print_format %8s %s\n" , 'char', 'name', 'unicode', 'utf-8 encoding'; map{ my $name = charinfo($_)->{'name'}; # get unicode name printf "$print_format %06x " , chr, lc $name, $_; my $utf8 = chr; # single char (using implicit $_) utf8::encode($utf8); # inplace encoding into utf8 parts map{ # for each utf8 char print ord printf " %x", ord; } split //, $utf8; print "\n"; } @chars;</lang>

Output:
 char  name                                 unicode  utf-8 encoding
    A  latin capital letter a               000041   41
    ΓΆ  latin small letter o with diaeresis  0000f6   c3 b6
    Π–  cyrillic capital letter zhe          000416   d0 96
    €  euro sign                            0020ac   e2 82 ac
    π„ž  musical symbol g clef                01d11e   f0 9d 84 9e

Phix

Standard autoinclude, see the manual and/or builtins/utfconv.e ( http://phix.x10.mx/docs/html/utfconv.htm and/or https://bitbucket.org/petelomax/phix/src )
As requested in the task description: <lang Phix>constant tests = {#0041, #00F6, #0416, #20AC, #1D11E}

function hex(sequence s, string fmt) -- output helper 

   for i=1 to length(s) do
       s[i] = sprintf(fmt,s[i])
   end for
   return join(s,',')

end function

for i=1 to length(tests) do 

   integer codepoint = tests[i]
   sequence s = utf32_to_utf8({codepoint}),
            r = utf8_to_utf32(s)
   printf(1,"#%04x -> {%s} -> {%s}\n",{codepoint, hex(s,"#%02x"),hex(r,"#%04x")})

end for</lang>

Output:
#0041 -> {#41} -> {#0041}
#00F6 -> {#C3,#B6} -> {#00F6}
#0416 -> {#D0,#96} -> {#0416}
#20AC -> {#E2,#82,#AC} -> {#20AC}
#1D11E -> {#F0,#9D,#84,#9E} -> {#1D11E}

Processing

<lang java>import java.nio.charset.StandardCharsets;

Integer[] code_points = {0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E};

void setup() { 

 size(850, 230);
 background(255);
 fill(0);
 textSize(16);
 int tel_1 = 80;
 int tel_2 = 50;
 text("Char     Name                                                            Unicode          UTF-8 (encoding)      Decoded", 40, 40);
 for (int cp : code_points) {  
   byte[] encoded = new String(new int[]{cp}, 0, 1).getBytes(StandardCharsets.UTF_8);
   for (byte b : encoded) {                                                    
     text(hex(b), tel_2+530, tel_1);
     tel_2 += 30;
   }
   text(char(cp), 50, tel_1);
   text(Character.getName(cp), 100, tel_1);
   String unicode = hex(cp);
   while (unicode.length() > 4 && unicode.indexOf("0") == 0) unicode = unicode.substring(1);
   text("U+"+unicode, 450, tel_1);
   Character decoded = char(new String(encoded, StandardCharsets.UTF_8).codePointAt(0));
   text(decoded, 750, tel_1);
   tel_1 += 30;  tel_2 = 50;
 }

}</lang>


PureBasic

The encoding and decoding procedure are kept simple and designed to work with an array of 5 elements for input/output of the UTF-8 encoding for a single code point at a time. It was decided not to use a more elaborate example that would have been able to operate on a buffer to encode/decode more than one code point at a time.

<lang purebasic>#UTF8_codePointMaxByteCount = 4 ;UTF-8 encoding uses only a maximum of 4 bytes to encode a codepoint

Procedure UTF8_encode(x, Array encoded_codepoint.a(1)) ;x is codepoint to encode, the array will contain output 

 ;Array encoded_codepoint() is used for output.
 ;After encode element zero holds the count of significant bytes in elements 1 to 4
 If ArraySize(encoded_codepoint()) < #UTF8_codePointMaxByteCount
   ReDim encoded_codepoint.a(#UTF8_codePointMaxByteCount)
 EndIf
 
 Select x
   Case 0 To $7F
     encoded_codepoint(0) = 1
     encoded_codepoint(1) = x ;all 7 bits
   Case $80 To $7FF
     encoded_codepoint(0) = 2
     encoded_codepoint(2) = (x & %00111111) | %10000000         ;lowest 6 bits
     encoded_codepoint(1) = (x >> 6) | %11000000                ;highest bits 7 -> 11
   Case $800 To $FFFF
     encoded_codepoint(0) = 3
     encoded_codepoint(3) = (x & %00111111) | %10000000         ;lowest 6 bits
     encoded_codepoint(2) = ((x >> 6) & %00111111) | %10000000  ;bits 7 -> 12
     encoded_codepoint(1) = (x >> 12) | %11100000               ;highest bits 13 -> 16
     
   Case $10000 To $10FFFF
     encoded_codepoint(0) = 4
     encoded_codepoint(4) = (x & %00111111) | %10000000         ;lowest 6 bits
     encoded_codepoint(3) = ((x >> 6) & %00111111) | %10000000  ;bits 7 -> 12
     encoded_codepoint(2) = ((x >> 12) & %00111111) | %10000000 ;bits 13 -> 18
     encoded_codepoint(1) = (x >> 18) | %11110000               ;highest bits 19 -> 21
   Default                                      
     encoded_codepoint(0) = 0  ;error, codepoint is not valid and can't be encoded
 EndSelect

EndProcedure

Procedure UTF8_decode(Array encoded_codepoint.a(1)) 

 ;Array encoded_codepoint() holds the UTF-8 encoding in elements 1 to 4, element zero isn't used for decoding.
 Protected x = -1 ;initialzie with error value for possible improper encoding
 
 If ArraySize(encoded_codepoint()) < #UTF8_codePointMaxByteCount
   ProcedureReturn x ;Input array was not dimensioned properly.
 EndIf
 
 ;Determine the number of bytes in the UTF8 encoding by looking at first byte
 ;and then proceeding accordingly.
 Select encoded_codepoint(1)
   Case %00000000 To %01111111 ;1 byte encoding
     x = encoded_codepoint(1)
   Case %11000000 To %11011111 ;2 byte encoding
     x = (encoded_codepoint(1) & %00011111) << 6 ;last 5 bits only
     x | (encoded_codepoint(2) & %00111111)
   Case %11100000 To %11101111 ;3 byte encoding
     x = (encoded_codepoint(1) & %00001111) << 6 ;last 4 bits only
     x << 6 + (encoded_codepoint(2) & %00111111) 
     x << 6 + (encoded_codepoint(3) & %00111111) 
   Case %11110000 To %11110111 ;4 byte encoding
     x = (encoded_codepoint(1) & %00000111) << 6 ;last 3 bits only
     x << 6 + (encoded_codepoint(2) & %00111111) 
     x << 6 + (encoded_codepoint(3) & %00111111) 
     x << 6 + (encoded_codepoint(4) & %00111111) 
 EndSelect
 
 ProcedureReturn x

EndProcedure

helper procedure to format output for this example

Procedure.s formatOutput(c$, c, Array encoded_utf.a(1), dcp) ;character, codepooint, UTf8 encoding, decoded codepoint 

 Protected o$, i, encoding$
 
 o$ = "   " + LSet(c$, 8) + LSet("U+" + RSet(Hex(c), 5, "0"), 10)
 For i = 1 To encoded_utf(0)
   encoding$ + RSet(Hex(encoded_utf(i)), 2, "0") + " "
 Next
 o$ + "  " + LSet(encoding$, 11, " ") + "   " + RSet(Hex(dcp), 5, "0")
 
 ProcedureReturn o$

EndProcedure

DataSection 

 ;unicode code points in hex
 unicode_codepoints:
 Data.i 5, $41, $F6, $416, $20AC, $1D11E
 ;The names for these codepoints are: latin capital letter a; latin small letter o With diaeresis
 ;cyrillic capital letter zhe; euro sign; musical symbol g clef.

EndDataSection

read initial unicode codepoint values

Restore unicode_codepoints Read num_codepoints num_codepoints - 1

Dim codepoint(num_codepoints) For i = 0 To num_codepoints 

 Read codepoint(i)

Next

This array is used for input and output from the UTF8 encode and decode procedures. After encoding its elements
hold the byte count of the encoding followed by the respective bytes. For decoding element zero is not used and
elements 1 To 4 holds the bytes to be decoded.

Dim encoded_codepoint.a(#UTF8_codePointMaxByteCount) If OpenConsole("", #PB_UTF8) 

 PrintN(LSet("", 11) + LSet("Unicode", 12) + LSet("UTF-8",14) + LSet("Decoded",12))
 PrintN(LSet("Character", 11) + LSet("Code Point", 12) + LSet("Encoding",14) + LSet("Code Point",12))
 PrintN(LSet("---------", 11) + LSet("----------", 12) + LSet("-----------",14) + LSet("-----------",12))
 
 For i = 0 To num_codepoints
   UTF8_encode(codepoint(i), encoded_codepoint())
   dcp = UTF8_decode(encoded_codepoint()) ;Decoded UTF-8 encoding should match original codepoint that was encoded.
   PrintN(formatOutput(Chr(codepoint(i)), codepoint(i), encoded_codepoint(), dcp))
 Next
 Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
 CloseConsole()

EndIf</lang> Sample output: 

           Unicode     UTF-8         Decoded
Character  Code Point  Encoding      Code Point
---------  ----------  -----------   -----------
   A       U+00041     41            00041
   ΓΆ       U+000F6     C3 B6         000F6
   ?       U+00416     D0 96         00416
   ?       U+020AC     E2 82 AC      800AC
   ?       U+1D11E     F0 9D 84 9E   1D11E

Python

<lang python>

  1. !/usr/bin/env python3

from unicodedata import name


def unicode_code(ch): 

   return 'U+{:04x}'.format(ord(ch))


def utf8hex(ch): 

   return " ".join([hex(c)[2:] for c in ch.encode('utf8')]).upper()


if __name__ == "__main__": 

   print('{:<11} {:<36} {:<15} {:<15}'.format('Character', 'Name', 'Unicode', 'UTF-8 encoding (hex)'))
   chars = ['A', 'ΓΆ', 'Π–', '€', 'π„ž']
   for char in chars:
       print('{:<11} {:<36} {:<15} {:<15}'.format(char, name(char), unicode_code(char), utf8hex(char)))</lang>
Output:
Character   Name                                 Unicode         UTF-8 encoding (hex)
A           LATIN CAPITAL LETTER A               U+0041          41             
ΓΆ           LATIN SMALL LETTER O WITH DIAERESIS  U+00f6          C3 B6          
Π–           CYRILLIC CAPITAL LETTER ZHE          U+0416          D0 96          
€           EURO SIGN                            U+20ac          E2 82 AC       
π„ž           MUSICAL SYMBOL G CLEF                U+1d11e         F0 9D 84 9E

Racket

<lang racket>#lang racket

(define char-map 

 '((LATIN-CAPITAL-LETTER-A              .  #\U0041)
   (LATIN-SMALL-LETTER-O-WITH-DIAERESIS .  #\U00F6)
   (CYRILLIC-CAPITAL-LETTER-ZHE         .  #\U0416)
   (EURO-SIGN                           .  #\U20AC)
   (MUSICAL-SYMBOL-G-CLEF               .  #\U1D11E)))

(for ((name.char (in-list char-map))) 

 (define name (car name.char))
 (define chr (cdr name.char))
 (let ((bites (bytes->list (string->bytes/utf-8 (list->string (list chr))))))
   (printf "~s\t~a\t~a\t~a\t~a~%" chr chr
           (map (curryr number->string 16) bites)
           (bytes->string/utf-8 (list->bytes bites))
           name)))</lang>
Output:
#\A	A	(41)	A	LATIN-CAPITAL-LETTER-A
#\ΓΆ	ΓΆ	(c3 b6)	ΓΆ	LATIN-SMALL-LETTER-O-WITH-DIAERESIS
#\Π–	Π–	(d0 96)	Π–	CYRILLIC-CAPITAL-LETTER-ZHE
#\€	€	(e2 82 ac)	€	EURO-SIGN
#\π„ž	π„ž	(f0 9d 84 9e)	π„ž	MUSICAL-SYMBOL-G-CLEF

Raku

(formerly Perl 6)

Works with: Rakudo version 2017.02

Pretty much all built in to the language. <lang perl6>say sprintf("%-18s %-36s|%8s| %7s |%14s | %s\n", 'Character|', 'Name', 'Ordinal', 'Unicode', 'UTF-8 encoded', 'decoded'), '-' x 100;

for < A ΓΆ Π– € π„ž 😜 πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦> -> $char { 

   printf "   %-5s | %-43s | %6s | %-7s | %12s  |%4s\n", $char, $char.uninames.join(','), $char.ords.join(' '),
     ('U+' X~ $char.ordsΒ».base(16)).join(' '), $char.encode('UTF8').listΒ».base(16).Str, $char.encode('UTF8').decode;

}</lang>

Output:
Character|         Name                                | Ordinal| Unicode | UTF-8 encoded | decoded
----------------------------------------------------------------------------------------------------
   A     | LATIN CAPITAL LETTER A                      |     65 | U+41    |           41  |   A
   ΓΆ     | LATIN SMALL LETTER O WITH DIAERESIS         |    246 | U+F6    |        C3 B6  |   ΓΆ
   Π–    | CYRILLIC CAPITAL LETTER ZHE                 |   1046 | U+416   |        D0 96  |   Π–
   €     | EURO SIGN                                   |   8364 | U+20AC  |     E2 82 AC  |   €
   π„ž     | MUSICAL SYMBOL G CLEF                       | 119070 | U+1D11E |  F0 9D 84 9E  |   π„ž
   😜    | FACE WITH STUCK-OUT TONGUE AND WINKING EYE  | 128540 | U+1F61C |  F0 9F 98 9C  |   😜
   πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦    | MAN,ZERO WIDTH JOINER,WOMAN,ZERO WIDTH JOINER,GIRL,ZERO WIDTH JOINER,BOY | 128104 8205 128105 8205 128103 8205 128102 | U+1F468 U+200D U+1F469 U+200D U+1F467 U+200D U+1F466 | F0 9F 91 A8 E2 80 8D F0 9F 91 A9 E2 80 8D F0 9F 91 A7 E2 80 8D F0 9F 91 A6  |   πŸ‘¨β€πŸ‘©β€πŸ‘§β€πŸ‘¦

Ruby

<lang ruby> character_arr = ["A","ΓΆ","Π–","€","π„ž"] for c in character_arr do 

   puts "Character: " + c.encode("utf-8")
   puts "Code-Point: #{c.encode("utf-8").ord.to_s(16).upcase}"
   puts "Code-Units: " + c.each_byte.map { |n| '%02X ' % (n & 0xFF) }.join
   puts ""

end </lang>

Output:
Character: A
Code-Point: 41
Code-Units: 41 

Character: ΓΆ
Code-Point: F6
Code-Units: C3 B6 

Character: Π–
Code-Point: 416
Code-Units: D0 96 

Character: €
Code-Point: 20AC
Code-Units: E2 82 AC 

Character: π„ž
Code-Point: 1D11E
Code-Units: F0 9D 84 9E

Rust

<lang rust>fn main() { 

   let chars = vec!('A', 'ΓΆ', 'Π–', '€', 'π„ž');
   chars.iter().for_each(|c| {
       let mut encoded = vec![0; c.len_utf8()];
       c.encode_utf8(&mut encoded);
       let decoded = String::from_utf8(encoded.to_vec()).unwrap();
       let encoded_string = encoded.iter().fold(String::new(), |acc, val| format!("{}{:X}", acc, val));
       println!("Character: {}, Unicode:{}, UTF-8 encoded:{}, Decoded: {}", c, c.escape_unicode(), encoded_string , decoded);
   });

} </lang>

Output:
Character: A, Unicode:\u{41}, UTF-8 encoded:41, Decoded: A
Character: ΓΆ, Unicode:\u{f6}, UTF-8 encoded:C3B6, Decoded: ΓΆ
Character: Π–, Unicode:\u{416}, UTF-8 encoded:D096, Decoded: Π–
Character: €, Unicode:\u{20ac}, UTF-8 encoded:E282AC, Decoded: €
Character: π„ž, Unicode:\u{1d11e}, UTF-8 encoded:F09D849E, Decoded: π„ž

Scala

Imperative solution

<lang scala>object UTF8EncodeAndDecode extends App { 

 val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)

 def utf8Encode(codepoint: Int): Array[Byte] =
   new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)

 def utf8Decode(bytes: Array[Byte]): Int =
   new String(bytes, StandardCharsets.UTF_8).codePointAt(0)

 println("Char Name                                 Unicode  UTF-8       Decoded")
 for (codePoint <- codePoints) {
   val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
   val bytes = utf8Encode(codePoint)

   def leftAlignedHex = f"U+${codePoint}%04X"

   val s = new StringBuilder()
   bytes.foreach(byte => s ++= "%02X ".format(byte))

   printf(s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n",
     codePoint, Character.getName(codePoint), leftAlignedHex, s, utf8Decode(bytes))
 }</lang>

Functional solution

<lang scala>import java.nio.charset.StandardCharsets

object UTF8EncodeAndDecode extends App { 

 val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)

 def utf8Encode(codepoint: Int): Array[Byte] =
   new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)

 def utf8Decode(bytes: Array[Byte]): Int =
   new String(bytes, StandardCharsets.UTF_8).codePointAt(0)

 println("Char Name                                 Unicode  UTF-8       Decoded")
 codePoints.foreach{ codePoint =>
   val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
   val bytes = utf8Encode(codePoint)

   def leftAlignedHex: String = f"U+${codePoint}%04X"

   def utf: String = bytes.foldLeft("")(_ + "%02X ".format(_))

   printf(s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n",
     codePoint, Character.getName(codePoint), leftAlignedHex, utf, utf8Decode(bytes))  }

 println(s"\nSuccessfully completed without errors. [total ${scala.compat.Platform.currentTime - executionStart} ms]")

}</lang>

Composable and testable solution

<lang scala>package example

object UTF8EncodeAndDecode extends TheMeat with App { 

 val codePoints = Seq(0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E)

 println("Char Name                                 Unicode  UTF-8       Decoded")
 codePoints.foreach { codepoint => print(composeString(codepoint)) }

 println(s"\nSuccessfully completed without errors. [total ${scala.compat.Platform.currentTime - executionStart} ms]")

}

trait TheMeat { 

 import java.nio.charset.StandardCharsets

 def composeString(codePoint: Int): String = {
   val w = if (Character.isBmpCodePoint(codePoint)) 4 else 5 // Compute spacing
   val bytes = utf8Encode(codePoint)

   def leftAlignedHex: String = f"U+${codePoint}%04X"

   def utf: String = bytes.foldLeft("")(_ + "%02X ".format(_))

   s"%-${w}c %-36s %-7s  %-${16 - w}s%c%n"
     .format(codePoint, Character.getName(codePoint), leftAlignedHex, utf, utf8Decode(bytes))
 }

 def utf8Encode(codepoint: Int): Array[Byte] =
   new String(Array[Int](codepoint), 0, 1).getBytes(StandardCharsets.UTF_8)

 def utf8Decode(bytes: Array[Byte]): Int =
   new String(bytes, StandardCharsets.UTF_8).codePointAt(0)

} </lang>

Seed7

<lang seed7>$ include "seed7_05.s7i"; 

 include "unicode.s7i";
 include "console.s7i";
 include "bytedata.s7i";

const proc: main is func 

 local
   var char: ch is ' ';
   var string: utf8 is "";
 begin
   OUT := STD_CONSOLE;
   writeln("Character  Unicode  UTF-8 encoding (hex)  Decoded");
   writeln("-------------------------------------------------");
   for ch range "AΓΆΠ–β‚¬π„ž" do
     utf8 := striToUtf8(str(ch));
     writeln(ch rpad 11 <& "U+" <& ord(ch) radix 16 lpad0 4 rpad 7 <&
             hex(utf8) rpad 22 <& utf8ToStri(utf8));
   end for;
 end func;</lang>
Output:
Character  Unicode  UTF-8 encoding (hex)  Decoded
-------------------------------------------------
A          U+0041   41                    A
ΓΆ          U+00f6   c3b6                  ΓΆ
Π–          U+0416   d096                  Π–
€          U+20ac   e282ac                €
π„ž          U+1d11e  f09d849e              π„ž

Sidef

<lang ruby>func utf8_encoder(Number code) { 

   code.chr.encode('UTF-8').bytes.map{.chr}

}

func utf8_decoder(Array bytes) { 

   bytes.map{.ord}.decode('UTF-8')

}

for n in ([0x0041, 0x00F6, 0x0416, 0x20AC, 0x1D11E]) { 

   var encoded = utf8_encoder(n)
   var decoded = utf8_decoder(encoded)
   assert_eq(n, decoded.ord)
   say "#{decoded} -> #{encoded}"

}</lang>

Output:
A -> ["A"]
ΓΆ -> ["\xC3", "\xB6"]
Π– -> ["\xD0", "\x96"]
€ -> ["\xE2", "\x82", "\xAC"]
π„ž -> ["\xF0", "\x9D", "\x84", "\x9E"]

Swift

In Swift there's a difference between UnicodeScalar, which is a single unicode code point, and Character which may consist out of multiple UnicodeScalars, usually because of combining characters. <lang Swift>import Foundation

func encode(_ scalar: UnicodeScalar) -> Data { 

 return Data(String(scalar).utf8)

}

func decode(_ data: Data) -> UnicodeScalar? { 

 guard let string = String(data: data, encoding: .utf8) else {
   assertionFailure("Failed to convert data to a valid String")
   return nil
 }
 assert(string.unicodeScalars.count == 1, "Data should contain one scalar!")
 return string.unicodeScalars.first

}

for scalar in "AΓΆΠ–β‚¬π„ž".unicodeScalars { 

 let bytes = encode(scalar)
 let formattedBytes = bytes.map({ String($0, radix: 16)}).joined(separator: " ")
 let decoded = decode(bytes)!
 print("character: \(decoded), code point: U+\(String(scalar.value, radix: 16)), \tutf-8: \(formattedBytes)")

} </lang>

Output:
character: A, code point: U+41, 	utf-8: 41
character: ΓΆ, code point: U+f6, 	utf-8: c3 b6
character: Π–, code point: U+416, 	utf-8: d0 96
character: €, code point: U+20ac, 	utf-8: e2 82 ac
character: π„ž, code point: U+1d11e, 	utf-8: f0 9d 84 9e

Tcl

Note: Tcl can handle Unicodes only up to U+FFFD, i.e. the Basic Multilingual Plane (BMP, 16 bits wide). Therefore, the fifth test fails as expected. <lang Tcl>proc encoder int { 

  set u [format %c $int]
  set bytes {}
  foreach byte [split [encoding convertto utf-8 $u] ""] {
     lappend bytes [format %02X [scan $byte %c]]
  }
  return $bytes

} proc decoder bytes { 

  set str {}
  foreach byte $bytes {
     append str [format %c [scan $byte %x]]
  }
  return [encoding convertfrom utf-8 $str]

} foreach test {0x0041 0x00f6 0x0416 0x20ac 0x1d11e} { 

  set res $test
  lappend res [encoder $test] -> [decoder [encoder $test]]
  puts $res

}</lang> 

0x0041 41 -> A
0x00f6 {C3 B6} -> ΓΆ
0x0416 {D0 96} -> Π–
0x20ac {E2 82 AC} -> €
0x1d11e {EF BF BD} -> οΏ½

Alternative Implementation

While perhaps not as readable as the above, this version handles beyond-BMP codepoints by manually composing the utf-8 byte sequences and emitting raw bytes to the console. encoding convertto utf-8 command still does the heavy lifting where it can.

<lang Tcl>proc utf8 {codepoint} { 

   scan $codepoint %llx cp
   if {$cp < 0x10000} {
       set str [subst \\u$codepoint]               ;# substitute per Tcl backslash rule
       set bytes [encoding convertto utf-8 $str]   ;# encode
   } else {                                        ;# codepoints beyond the BMP need manual approach
       set bits [format %021b $cp]                 ;# format as binary string
       set unibits    11110[string range $bits 0 2];# insert extra bits for utf-8 4-byte encoding
       append unibits 10[string range $bits 3 8]
       append unibits 10[string range $bits 9 14]
       append unibits 10[string range $bits 15 20]
       set bytes [binary format B* $unibits]       ;# turn into a sequence of bytes
   }
   return $bytes

}

proc hexchars {s} { 

   binary scan $s H* hex
   regsub -all .. $hex {\0 }

}

  1. for the test, we assume the tty is in utf-8 mode and can handle beyond-BMP chars
  2. so set output mode to binary so we can write raw bytes!

chan configure stdout -encoding binary foreach codepoint { 41 F6 416 20AC 1D11E } { 

   set utf8 [utf8 $codepoint]
   puts "[format U+%04s $codepoint]\t$utf8\t[hexchars $utf8]"

}</lang>

Output:
U+0041  A       41

U+00F6  ΓΆ       c3 b6
U+0416  Π–       d0 96
U+20AC  €       e2 82 ac
U+1D11E π„ž       f0 9d 84 9e

VBA

<lang VB>Private Function unicode_2_utf8(x As Long) As Byte() 

   Dim y() As Byte
   Dim r As Long
   Select Case x
       Case 0 To &H7F
           ReDim y(0)
           y(0) = x
       Case &H80 To &H7FF
           ReDim y(1)
           y(0) = 192 + x \ 64
           y(1) = 128 + x Mod 64
       Case &H800 To &H7FFF
           ReDim y(2)
           y(2) = 128 + x Mod 64
           r = x \ 64
           y(1) = 128 + r Mod 64
           y(0) = 224 + r \ 64
       Case 32768 To 65535 '&H8000 To &HFFFF equals in VBA as -32768 to -1
           ReDim y(2)
           y(2) = 128 + x Mod 64
           r = x \ 64
           y(1) = 128 + r Mod 64
           y(0) = 224 + r \ 64
       Case &H10000 To &H10FFFF
           ReDim y(3)
           y(3) = 128 + x Mod 64
           r = x \ 64
           y(2) = 128 + r Mod 64
           r = r \ 64
           y(1) = 128 + r Mod 64
           y(0) = 240 + r \ 64
       Case Else
           MsgBox "what else?" & x & " " & Hex(x)
   End Select
   unicode_2_utf8 = y

End Function Private Function utf8_2_unicode(x() As Byte) As Long 

   Dim first As Long, second As Long, third As Long, fourth As Long
   Dim total As Long
   Select Case UBound(x) - LBound(x)
       Case 0 'one byte
           If x(0) < 128 Then
               total = x(0)
           Else
               MsgBox "highest bit set error"
           End If
       Case 1 'two bytes and assume first byte is leading byte
           If x(0) \ 32 = 6 Then
               first = x(0) Mod 32
               If x(1) \ 64 = 2 Then
                   second = x(1) Mod 64
               Else
                   MsgBox "mask error"
               End If
           Else
               MsgBox "leading byte error"
           End If
           total = 64 * first + second
       Case 2 'three bytes and assume first byte is leading byte
           If x(0) \ 16 = 14 Then
               first = x(0) Mod 16
               If x(1) \ 64 = 2 Then
                   second = x(1) Mod 64
                   If x(2) \ 64 = 2 Then
                       third = x(2) Mod 64
                   Else
                       MsgBox "mask error last byte"
                   End If
               Else
                   MsgBox "mask error middle byte"
               End If
           Else
               MsgBox "leading byte error"
           End If
               total = 4096 * first + 64 * second + third
       Case 3 'four bytes and assume first byte is leading byte
           If x(0) \ 8 = 30 Then
               first = x(0) Mod 8
               If x(1) \ 64 = 2 Then
                   second = x(1) Mod 64
                   If x(2) \ 64 = 2 Then
                       third = x(2) Mod 64
                       If x(3) \ 64 = 2 Then
                           fourth = x(3) Mod 64
                       Else
                           MsgBox "mask error last byte"
                       End If
                   Else
                       MsgBox "mask error third byte"
                   End If
               Else
                   MsgBox "mask error second byte"
               End If
           Else
               MsgBox "mask error leading byte"
           End If
           total = CLng(262144 * first + 4096 * second + 64 * third + fourth)
       Case Else
           MsgBox "more bytes than expected"
       End Select
       utf8_2_unicode = total

End Function Public Sub program() 

   Dim cp As Variant
   Dim r() As Byte, s As String
   cp = [{65, 246, 1046, 8364, 119070}] '[{&H0041,&H00F6,&H0416,&H20AC,&H1D11E}]
   Debug.Print "ch  unicode  UTF-8 encoded  decoded"
   For Each cpi In cp
       r = unicode_2_utf8(CLng(cpi))
       On Error Resume Next
       s = CStr(Hex(cpi))
       Debug.Print ChrW(cpi); String$(10 - Len(s), " "); s,
       If Err.Number = 5 Then Debug.Print "?"; String$(10 - Len(s), " "); s,
       s = ""
       For Each yz In r
           s = s & CStr(Hex(yz)) & " "
       Next yz
       Debug.Print String$(13 - Len(s), " "); s;
       s = CStr(Hex(utf8_2_unicode(r)))
       Debug.Print String$(8 - Len(s), " "); s
   Next cpi

End Sub</lang>

Output:
ch  unicode  UTF-8 encoded  decoded

A        41             41       41
ΓΆ        F6          C3 B6       F6
?       416          D0 96      416
€      20AC       E2 82 AC     20AC
?     1D11E    F0 9D 84 9E    1D11E

Wren

The utf8_decode function was translated from the Go entry. <lang ecmascript>import "/fmt" for Fmt

var utf8_encode = Fn.new { |cp| String.fromCodePoint(cp).bytes.toList }

var utf8_decode = Fn.new { |b| 

   var mbMask = 0x3f // non-first bytes start 10 and carry 6 bits of data
   var b0 = b[0]
   if (b0 < 0x80) {
       return b0
   } else if (b0 < 0xe0) {
       var b2Mask = 0x1f // first byte of a 2-byte encoding starts 110 and carries 5 bits of data
       return (b0 & b2Mask) <<  6 | (b[1] & mbMask)
   } else if (b0 < 0xf0) {
       var b3Mask = 0x0f // first byte of a 3-byte encoding starts 1110 and carries 4 bits of data
       return (b0 & b3Mask) << 12 | (b[1] & mbMask) <<  6 | (b[2] & mbMask)
   } else {
       var b4Mask = 0x07 // first byte of a 4-byte encoding starts 11110 and carries 3 bits of data
       return (b0 & b4Mask) << 18 | (b[1] & mbMask) << 12 | (b[2] & mbMask) << 6 | (b[3] & mbMask)
   }

}

var tests = [ 

   ["LATIN CAPITAL LETTER A", 0x41],
   ["LATIN SMALL LETTER O WITH DIAERESIS", 0xf6],
   ["CYRILLIC CAPITAL LETTER ZHE", 0x416],
   ["EURO SIGN", 0x20ac],
   ["MUSICAL SYMBOL G CLEF", 0x1d11e]

]

System.print("Character Name Unicode UTF-8 encoding (hex)") System.print("---------------------------------------------------------------------------------")

for (test in tests) { 

   var cp = test[1]
   var bytes = utf8_encode.call(cp)
   var utf8 = bytes.map { |b| Fmt.Xz(2, b) }.join(" ")
   var cp2 = utf8_decode.call(bytes)
   var uni = String.fromCodePoint(cp2)
   System.print("%(Fmt.s(-11, uni)) %(Fmt.s(-37, test[0])) U+%(Fmt.s(-8, Fmt.Xz(4, cp2))) %(utf8)")

}</lang>

Output:
Character   Name                                  Unicode    UTF-8 encoding (hex)
---------------------------------------------------------------------------------
A           LATIN CAPITAL LETTER A                U+0041     41
ΓΆ           LATIN SMALL LETTER O WITH DIAERESIS   U+00F6     C3 B6
Π–           CYRILLIC CAPITAL LETTER ZHE           U+0416     D0 96
€           EURO SIGN                             U+20AC     E2 82 AC
π„ž           MUSICAL SYMBOL G CLEF                 U+1D11E    F0 9D 84 9E

zkl

<lang zkl>println("Char Unicode UTF-8"); foreach utf,unicode_int in (T( T("\U41;",0x41), T("\Uf6;",0xf6), 

     T("\U416;",0x416), T("\U20AC;",0x20ac), T("\U1D11E;",0x1d11e))){
  utf_int:=utf.reduce(fcn(s,c){ 0x100*s + c.toAsc() },0);
  char :=unicode_int.toString(-8);	// Unicode int to UTF-8 string
  // UTF-8 bytes to UTF-8 string:
  char2:=Data(Void,utf_int.toBigEndian(utf_int.len())).text;

  println("%s %s %9s  %x".fmt(char,char2,"U+%x".fmt(unicode_int),utf_int));

}</lang> Int.len() --> number of bytes in int. This could be hard coded because UTF-8 has a max of 6 bytes and (0x41).toBigEndian(6) --> 0x41,0,0,0,0,0 which is a zero terminated string ("A");

Output:
Char  Unicode  UTF-8
A A      U+41  41
ΓΆ ΓΆ      U+f6  c3b6
Π– Π–     U+416  d096
€ €    U+20ac  e282ac
π„ž π„ž   U+1d11e  f09d849e
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