String length: Difference between revisions

Content added Content deleted

Inline

Revision as of 07:52, 19 June 2008

In this task, the goal is to find the character and byte length of a string. This means encodings like UTF-8 need to be handled properly, as there is not necessarily a one-to-one relationship between bytes and characters. For example, the character length of "møøse" is 5 but the byte length is 7 in UTF-8 and 10 in UTF-16.

Please mark your examples with ===Character Length=== or ===Byte Length===.

4D

Byte Length

$length:=Length("Hello, world!")

ActionScript

Character Length

myStrVar.length()

Ada

Works with: GCC version 4.1.2

Byte Length

<ada>

Str    : String := "Hello World";
Length : constant Natural := Str'Size / 8;

</ada> The 'Size attribute returns the size of an object in bits. Provided that under "byte" one understands an octet of bits, the length in "bytes" will be 'Size divided to 8. Note that this is not necessarily the machine storage unit. In order to make the program portable, System.Storage_Unit should be used instead of "magic number" 8. System.Storage_Unit yields the number of bits in a storage unit on the current machine. Further, the length of a string object is not the length of what the string contains in whatever measurement units. String as an object may have a "dope" to keep the array bounds. In fact the object length can even be 0, if the compiler optimized the object away. So in most cases "byte length" makes no sense in Ada.

Character Length

<ada> Latin_1_Str : String := "Hello World"; UCS_16_Str : Wide_String := "Hello World"; Unicode_Str : Wide_Wide_String := "Hello World"; Latin_1_Length : constant Natural := Latin_1_Str'Length; UCS_16_Length : constant Natural := UCS_16_Str'Length; Unicode_Length : constant Natural := Unicode_Str'Length; </ada> The attribute 'Length yields the number of elements of an array. Since strings in Ada are arrays of characters, 'Length is the string length. Ada supports strings of Latin-1, UCS-16 and full Unicode characters. In the example above character length of all three strings is 11. The length of the objects in bits will differ.

ALGOL 68

Character Length

STRING str := "hello, world";
INT length := UPB str;
printf(($"Length of """g""" is "g(3)$,str,length))

Result:

Length of "hello, world" is +12

AppleScript

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

count of "Hello World"

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

count of "Hello World"

Or:

count "Hello World"

AWK

Byte Length

From within any code block:

w=length("Hello, world!")      # static string example
x=length("Hello," s " world!") # dynamic string example
y=length($1)                   # input field example
z=length(s)                    # variable name example

Ad hoc program from command line:

echo "Hello, wørld!" | awk '{print length($0)}'   # 14

From executable script: (prints for every line arriving on stdin)

#!/usr/bin/awk -f
{print"The length of this line is "length($0)}

BASIC

Character Length

Works with: QuickBasic version 4.5

BASIC only supports single-byte characters. The character "ø" is converted to "°" for printing to the console and length functions, but will still output to a file as "ø".

INPUT a$
PRINT LEN(a$)

C

Byte Length

Works with: ANSI C

Works with: GCC version 3.3.3

 #include <string.h>

 int main(void) 
 {
   const char *string = "Hello, world!";
   size_t length = strlen(string);
          
   return 0;
 }

or by hand:

 int main(void) 
 {
   const char *string = "Hello, world!";
   size_t length = 0;
   
   char *p = (char *) string;
   while (*p++ != '\0') length++;                                         
   
   return 0;
 }

or (for arrays of char only)

 #include <stdlib.h>
 
 int main(void)
 {
   char const s[] = "Hello, world!";
   size_t length = sizeof s - 1;
   
   return 0;
 }

Character Length

For wide character strings (usually Unicode uniform-width encodings such as UCS-2 or UCS-4):

 #include <stdio.h>
 #include <wchar.h>
 
 int main(void) 
 {
    wchar_t *s = L"\x304A\x306F\x3088\x3046"; /* Japanese hiragana ohayou */
    size_t length;
 
    length = wcslen(s);
    printf("Length in characters = %d\n", length);
    printf("Length in bytes      = %d\n", sizeof(s) * sizeof(wchar_t));
    
    return 0;
 }

TODO: non-standard library calls for system multi-byte encodings, such as _mbcslen()

C++

Byte Length

Works with: ISO C++

Works with: g++ version 4.0.2

 #include <string> // note: not <string.h>
 
 int main()
 {
   std::string s = "Hello, world!";
   std::string::size_type length = s.length(); // option 1: In Characters/Bytes
   std::string::size_type size = s.size();     // option 2: In Characters/Bytes
   // In bytes same as above since sizeof(char) == 1
   std::string::size_type bytes = s.length() * sizeof(std::string::value_type); 
 }

For wide character strings:

 #include <string>
 
 int main()
 {
   std::wstring s = L"\u304A\u306F\u3088\u3046";
   std::wstring::size_type length = s.length() * sizeof(std::wstring::value_type); // in bytes
 }

Character Length

Works with: ISO C++

Works with: g++ version 4.0.2

For wide character strings:

 #include <string>
 
 int main()
 {
   std::wstring s = L"\u304A\u306F\u3088\u3046";
   std::wstring::size_type length = s.length();
}

For narrow character strings and arbitrary locales:

Works with: ISO C++

Works with: g++ version 4.1.2 20061115 (prerelease) (SUSE Linux)

#include <cwchar>  // for mbstate_t
#include <locale>

// give the character length for a given named locale
std::size_t char_length(std::string const& text, char const* locale_name)
{
  // locales work on pointers; get length and data from string and
  // then don't touch the original string any more, to avoid
  // invalidating the data pointer
  std::size_t len = text.length();
  char const* input = text.data();

  // get the named locale
  std::locale loc(locale_name);

  // get the conversion facet of the locale
  typedef std::codecvt<wchar_t, char, std::mbstate_t> cvt_type;
  cvt_type const& cvt = std::use_facet<cvt_type>(loc);

  // allocate buffer for conversion destination
  std::size_t bufsize = cvt.max_length()*len;
  wchar_t* destbuf = new wchar_t[bufsize];
  wchar_t* dest_end;

  // do the conversion
  mbstate_t state = mbstate_t();
  cvt.in(state, input, input+len, input, destbuf, destbuf+bufsize, dest_end);

  // determine the length of the converted sequence
  std::size_t length = dest_end - destbuf;

  // get rid of the buffer
  delete[] destbuf;

  // return the result
  return length;
}

Example usage (note that the locale names are OS specific):

#include <iostream>

int main()
{
  // Tür (German for door) in UTF8
  std::cout << char_length("\x54\xc3\xbc\x72", "de_DE.utf8") << "\n"; // outputs 3

  // Tür in ISO-8859-1
  std::cout << char_length("\x54\xfc\x72", "de_DE") << "\n"; // outputs 3
}

Note that the strings are given as explicit hex sequences, so that the encoding used for the source code won't matter.

C#

Platform: .NET

Works with: C # version 1.0+

Byte Length

string s = "Hello, world!";
int blength = System.Text.Encoding.GetBytes(s).length; // In Bytes.

Character Length

string s = "Hello, world!";
int clength = s.Length;  // In characters

Clean

Byte Length

Clean Strings are unboxed arrays of characters. Characters are always a single byte. The function size returns the number of elements in an array.

import StdEnv

strlen :: String -> Int
strlen string = size string 

Start = strlen "Hello, world!"

ColdFusion

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

  #len("Hello World")#

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

  #len("Hello World")#

Common Lisp

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

  (length "Hello World")

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

  (length "Hello World")

Component Pascal

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

  LEN("Hello, World!")

E

Character Length

"Hello World".size()

Forth

Works with: ANS Forth

Byte Length

Strings in Forth come in two forms, neither of which are the null-terminated form commonly used in the C standard library.

Counted string

A counted string is a single pointer to a short string in memory. The string's first byte is the count of the number of characters in the string. This is how symbols are stored in a Forth dictionary.

 CREATE s ," Hello world" \ create string "s"
 s C@ ( -- length=11 )

Stack string

A string on the stack is represented by a pair of cells: the address of the string data and the length of the string data (in characters). The word COUNT converts a counted string into a stack string. The STRING utility wordset of ANS Forth works on these addr-len pairs. This representation has the advantages of not requiring null-termination, easy representation of substrings, and not being limited to 255 characters.

S" string" ( addr len)
DUP .   \ 6

Character Length

The 1994 ANS standard does not have any notion of a particular character encoding, although it distinguishes between character and machine-word addresses. (There is some ongoing work on standardizing an "XCHAR" wordset for dealing with strings in particular encodings such as UTF-8.)

The following code will count the number of UTF-8 characters in a null-terminated string. It relies on the fact that all bytes of a UTF-8 character except the first have the the binary bit pattern "10xxxxxx".

2 base !
: utf8+ ( str -- str )
  begin
    char+
    dup c@
    11000000 and
    10000000 <>
  until ;
decimal

: count-utf8 ( zstr -- n )
  0
  begin
    swap dup c@
  while
    utf8+
    swap 1+
  repeat drop ;

Haskell

Byte Length

It is not possible to determine the "byte length" of an ordinary string, because in Haskell, a string is a boxed list of unicode characters. So each character in a string is represented as whatever the compiler considers as the most efficient representation of a cons-cell and a unicode character, and not as a byte.

For efficient storage of sequences of bytes, there's Data.ByteString, which uses Word8 as a base type. Byte strings have an additional Data.ByteString.Char8 interface, which will truncate each Unicode Char to 8 bits as soon as it is converted to a byte string. However, this is not adequate for the task, because truncation simple will garble characters other than Latin-1, instead of encoding them into UTF-8, say.

There are several (non-standard, so far) Unicode encoding libraries available on Hackage. As an example, we'll use encoding-0.2, as Data.Encoding:

import Data.Encoding
import Data.ByteString as B

strUTF8  :: ByteString 
strUTF8  = encode UTF8  "Hello World!"

strUTF32 :: ByteString 
strUTF32 = encode UTF32 "Hello World!"

strlenUTF8  = B.length strUTF8
strlenUTF32 = B.length strUTF32

Character Length

Works with: GHCi version 6.6

Works with: Hugs

The base type Char defined by the standard is already intended for (plain) Unicode characters.

strlen = length "Hello, world!"

IDL

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

Compiler: any IDL compiler should do

 length = strlen("Hello, world!")

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 length = strlen("Hello, world!")

Java

Byte Length

Java encodes strings in UTF-16, which represents each character with one or two 16-bit values. The length method of String objects returns the number of 16-bit values used to encode a string, so the number of bytes can be determined by doubling that number.

String s = "Hello, world!";
int byteCount = s.length() * 2;

Another way to know the byte length of a string is to explicitly specify the charset we desire.

String s = "Hello, world!";
int byteCountUTF16 = s.getBytes("UTF-16").length;
int byteCountUTF8  = s.getBytes("UTF-8").length;

Character Length

Java encodes strings in UTF-16, which represents each character with one or two 16-bit values. The most commonly used characters are represented by one 16-bit value, while rarer ones like some mathematical symbols are represented by two.

The length method of String objects gives the number of 16-bit values used to encode a string.

String s = "Hello, world!";
int length = s.length();

Since Java 1.5, the actual number of characters can be determined by calling the codePointCount method.

String str = "\uD834\uDD2A"; //U+1D12A
int length1 = str.length(); //2
int length2 = str.codePointCount(0, str.length()); //1

JavaScript

Byte Length

JavaScript encodes strings in UTF-16, which represents each character with one or two 16-bit values. The length property of string objects gives the number of 16-bit values used to encode a string, so the number of bytes can be determined by doubling that number.

var s = "Hello, world!";
var byteCount = s.length * 2; //26

Character Length

JavaScript encodes strings in UTF-16, which represents each character with one or two 16-bit values. The most commonly used characters are represented by one 16-bit value, while rarer ones like some mathematical symbols are represented by two.

JavaScript has no built-in way to determine how many characters are in a string. However, if the string only contains commonly used characters, the number of characters will be equal to the number of 16-bit values used to represent the characters.

var str1 = "Hello, world!";
var len1 = str1.length; //13

var str2 = "\uD834\uDD2A"; //U+1D12A represented by a UTF-16 surrogate pair
var len2 = str2.length; //2

JudoScript

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 //Store length of hello world in length and print it
 . length = "Hello World".length();

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 //Store length of hello world in length and print it
 . length = "Hello World".length();

Logo

Logo is so old that only ASCII encoding is supported. Modern versions of Logo may have enhanced character set support.

print count "|Hello World|  ; 11
print count "møøse            ; 5
print char 248   ; ø - implies ISO-Latin character set

LSE64

Byte Length

LSE stores strings as arrays of characters in 64-bit cells plus a count.

" Hello world" @ 1 + 8 * ,   # 96 = (11+1)*(size of a cell) = 12*8

Character Length

LSE uses counted strings: arrays of characters, where the first cell contains the number of characters in the string.

" Hello world" @ ,   # 11

Lua

Works with: Lua version 5.0+

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 string="Hello world"
 length=#string

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 string="Hello world"
 length=#string

Mathematica

Character length

StringLength["Hello world"]

Byte length

StringByteCount["Hello world"]

MAXScript

Character Length

"Hello world".count

mIRC Scripting Language

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

alias stringlength { echo -a Your Name is: $len($$?="Whats your name") letters long! }

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

alias stringlength { echo -a Your Name is: $len($$?="Whats your name") letters long! }

Objective-C

Character Length

// Return the length in unicode characters
unsigned numberOfCharacters = [@"m\xf8\xf8se" length];  // 5

Byte Length

// Return the number of bytes depending on the encoding
unsigned numberOfBytes = [[@"m\xf8\xf8se" dataUsingEncoding:NSUTF8Encoding] length]; // 7

OCaml

Works with: Ocaml version 3.09

In OCaml currently, characters are bytes.

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

String.length "Hello world";;

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

String.length "Hello world";;

Perl

Byte Length

Works with: Perl version 5.8

Strings in Perl consist of characters. Measuring the byte length therefore requires conversion to some binary representation (called encoding, both noun and verb).

use utf8; # so we can use literal characters like ☺ in source
use Encode qw(encode);

print length encode 'UTF-8', "Hello, world! ☺";
# 17. The last character takes 3 bytes, the others 1 byte each.

print length encode 'UTF-16', "Hello, world! ☺";
# 32. 2 bytes for the BOM, then 15 byte pairs for each character.

Character Length

Works with: Perl version 5.X

 my $length = length "Hello, world!";

PHP

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 $length = strlen('Hello, world!');

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 $length = strlen('Hello, world!');

PL/SQL

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

DECLARE
  string VARCHAR2( 50 ) := 'Hello, world!';
  stringlength NUMBER;
BEGIN
  stringlength := length( string );
END;

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

DECLARE
  string VARCHAR2( 50 ) := 'Hello, world!';
  stringlength NUMBER;
BEGIN
  stringlength := length( string );
END;

Pop11

Byte Length

Currently Pop11 supports only strings consisting of 1-byte units. Strings can carry arbitrary binary data, so user can for example use UTF-8 (however builtin procedures will treat each byte as a single character). The length function for strings returns length in bytes:

lvars str = 'Hello, world!';
lvars len = length(str);

Python

Byte Length

Works with: Python version 2.x

Byte length depends on the encoding. Python use 2 or 4 bytes per character internally for unicode strings, depending on how it was built. The internal representation is not interesting for the user.

# The letter Alef
>>> len(u'\u05d0'.encode('utf-8'))
2
>>> len(u'\u05d0'.encode('iso-8859-8'))
1

Example from the problem statement:

#!/bin/env python
# -*- coding: UTF-8 -*-
s = u"møøse"
assert len(s) == 5
assert len(s.encode('UTF-8')) == 7
assert len(s.encode('UTF-16')) == 12 # The extra character is probably a leading Unicode byte-order mark (BOM).

Character Length

Works with: Python version 2.4

len() returns the number of characters in a unicode string or plain ascii string. To get the length of encoded string, you have to decode it first:

>>> len('ascii')
5
>>> len(u'\u05d0') # the letter Alef as unicode literal
1
>>> len('\xd7\x90'.decode('utf-8')) # Same encoded as utf-8 string
1

Ruby

Byte Length

 string="Hello world"
 print string.length

or

 puts "Hello World".length

Character Length

Library: active_support

 require 'active_support'
 puts "Hello World".chars.length

Scheme

Byte Length

Works with: Gauche version 0.8.7 [utf-8,pthreads]

string-size function is only Gauche function.

 (string-size "Hello world")

Character Length

Works with: Gauche version 0.8.7 [utf-8,pthreads]

string-length function is in R5RS, R6RS.

 (string-length "Hello world")

Seed7

Character Length

 length("Hello, world!")

Smalltalk

Byte Length

 string := 'Hello, world!'.
 string size.

Character Length

In GNU Smalltalk:

 string := 'Hello, world!".
 string numberOfCharacters.

requires loading the Iconv package:

 PackageLoader fileInPackage: 'Iconv'

Standard ML

Works with: SML/NJ version 110.60

Works with: Moscow ML version 2.01

Works with: MLton version 20061107

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

val strlen = size "Hello, world!";

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

val strlen = size "Hello, world!";

Tcl

Byte Length

Basic version:

 string bytelength "Hello, world!"

or more elaborately, needs Interpreter any 8.X. Tested on 8.4.12.

 fconfigure stdout -encoding utf-8; #So that Unicode string will print correctly
 set s1 "hello, world"
 set s2 "\u304A\u306F\u3088\u3046"
 puts [format "length of \"%s\" in bytes is %d"  $s1 [string bytelength $s1]]
 puts [format "length of \"%s\" in bytes is %d"  $s2 [string bytelength $s2]]

Character Length

Basic version:

 string length "Hello, world!"

or more elaborately, needs Interpreter any 8.X. Tested on 8.4.12.

 fconfigure stdout -encoding utf-8; #So that Unicode string will print correctly
 set s1 "hello, world"
 set s2 "\u304A\u306F\u3088\u3046"
 puts [format "length of \"%s\" in characters is %d"  $s1 [string length $s1]]
 puts [format "length of \"%s\" in characters is %d"  $s2 [string length $s2]]

Toka

Byte Length

 " hello, world!" string.getLength

UNIX Shell

Byte Length

With external utilities:

Works with: bourne shell

 string='Hello, world!'
 length=`echo -n "$string" | wc -c | tr -dc '0-9'`
 echo $length # if you want it printed to the terminal

With SUSv3 parameter expansion modifier:

Works with: Almquist SHell

Works with: Bourne Again SHell version 3.2

Works with: Korn SHell version 5.2.14 99/07/13.2

Works with: Z SHell

 string='Hello, world!'
 length="${#string}"
 echo $length # if you want it printed to the terminal

VBScript

Byte Length

LenB(string|varname)

Returns the number of bytes required to store a string in memory. Returns null if string|varname is null.

Character Length

Len(string|varname)

Returns the length of the string|varname . Returns null if string|varname is null.

XSLT

Character Length

<?xml version="1.0" encoding="UTF-8"?>
...
<xsl:value-of select="string-length('møøse')" />

xTalk

Works with: HyperCard

Byte Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 put the length of "Hello World"

or

 put the number of characters in "Hello World"

Character Length

This example may be incorrect due to a recent change in the task requirements or a lack of testing. Please verify it and remove this message. If the example does not match the requirements or does not work, replace this message with Template:incorrect or fix the code yourself.

 put the length of "Hello World"

or

 put the number of characters in "Hello World"