Terminal control/Unicode output
The task is to check that the terminal supports Unicode output, before outputting a Unicode character. If the terminal supports Unicode, then the terminal should output a Unicode delta (U+25b3). If the terminal does not support Unicode, then an appropriate error should be raised.
You are encouraged to solve this task according to the task description, using any language you may know.
Note that it is permissible to use system configuration data to determine terminal capabilities if the system provides such a facility.
Arturo
canHandleUnicode?: function [][
any? @[
if key? env "LC_ALL" -> contains? lower get env "LC_ALL" "utf-8"
if key? env "LC_CTYPE" -> contains? lower get env "LC_CTYPE" "utf-8"
if key? env "LANG" -> contains? lower get env "LANG" "utf-8"
]
]
if? canHandleUnicode? ->
print "Terminal handle unicode and U+25B3 is: △"
else ->
print "Unicode is not supported on this terminal"
- Output:
Terminal handle unicode and U+25B3 is: △
AutoHotkey
DllCall("AllocConsole")
hConsole:=DllCall("GetConsoleWindow","UPtr")
Stdout:=FileOpen(DllCall("GetStdHandle", "int", -11, "ptr"), "h `n")
Stdin:=FileOpen(DllCall("GetStdHandle", "int", -10, "ptr"), "h `n")
;Full Unicode-support font needed
e:=SetConsoleOutputCP(65001)
if (e && A_IsUnicode)
{
Print("△ - Unicode delta (U+25b3)")
GetPos(x,y)
if (x=0 && y=0) ;nothing prints if Non-Unicode font
Print("Non-Unicode font")
}
else
Print("Unicode not supported")
Pause()
Print(string=""){
global Stdout
if (!StrLen(string))
return 1
e:=DllCall("WriteConsole" . ((A_IsUnicode) ? "W" : "A")
, "UPtr", Stdout.__Handle
, "Str", string
, "UInt", strlen(string)
, "UInt*", Written
, "uint", 0)
if (!e) or (ErrorLevel)
return 0 ;Failure
Stdout.Read(0)
return e
}
SetConsoleOutputCP(codepage) {
e:=DllCall("SetConsoleOutputCP","UInt",codepage)
if (!e) or (ErrorLevel)
return 0 ;Failure
return 1
}
GetPos(ByRef x, ByRef y) {
global Stdout
VarSetCapacity(struct,22,0)
e:=DllCall("GetConsoleScreenBufferInfo","UPtr",Stdout.__Handle,"Ptr",&struct)
if (!e) or (ErrorLevel)
return 0 ;Failure
x:=NumGet(&struct,4,"UShort")
y:=NumGet(&struct,6,"UShort")
return 1
}
Pause() {
RunWait, %comspec% /c pause>NUL
}
AWK
#!/usr/bin/awk -f
BEGIN {
unicodeterm=1 # Assume Unicode support
if (ENVIRON["LC_ALL"] !~ "UTF") {
if (ENVIRON["LC_ALL"] != ""
unicodeterm=0 # LC_ALL is the boss, and it says nay
else {
# Check other locale settings if LC_ALL override not set
if (ENVIRON["LC_CTYPE"] !~ "UTF") {
if (ENVIRON["LANG"] !~ "UTF")
unicodeterm=0 # This terminal does not support Unicode
}
}
}
if (unicodeterm) {
# This terminal supports Unicode
# We need a Unicode compatible printf, so we source this externally
# printf might not know \u or \x, so use octal.
# U+25B3 => UTF-8 342 226 263
"/usr/bin/printf \\342\\226\\263\\n"
} else {
print "HW65001 This program requires a Unicode compatible terminal"|"cat 1>&2"
exit 252 # Incompatible hardware
}
BaCon
LANG
environment test borrowed from C solution.
' Determine if the terminal supports Unicode
' if so display delta, if not display error message
LET lc$ = GETENVIRON$("LANG")
IF INSTR(LCASE$(lc$), "utf8") != 0 THEN
PRINT UTF8$(0x25B3)
ELSE
EPRINT "Sorry, terminal is not testing as unicode ready"
END IF
BBC BASIC
VDU 23,22,640;512;8,16,16,128+8 : REM Enable UTF-8 mode
*FONT Arial Unicode MS,36
PRINT CHR$(&E2)+CHR$(&96)+CHR$(&B3)
C
#include<stdlib.h>
#include<stdio.h>
int
main ()
{
int i;
char *str = getenv ("LANG");
for (i = 0; str[i + 2] != 00; i++)
{
if ((str[i] == 'u' && str[i + 1] == 't' && str[i + 2] == 'f')
|| (str[i] == 'U' && str[i + 1] == 'T' && str[i + 2] == 'F'))
{
printf
("Unicode is supported on this terminal and U+25B3 is : \u25b3");
i = -1;
break;
}
}
if (i != -1)
printf ("Unicode is not supported on this terminal.");
return 0;
}
Output:
Unicode is supported on this terminal and U+25B3 is : â³
Clojure
(if-not (empty? (filter #(and (not (nil? %)) (.contains (.toUpperCase %) "UTF"))
(map #(System/getenv %) ["LANG" "LC_ALL" "LC_CTYPE"])))
"Unicode is supported on this terminal and U+25B3 is : \u25b3"
"Unicode is not supported on this terminal.")
- Output:
"Unicode is supported on this terminal and U+25B3 is : △"
Common Lisp
Each implementation has a different "getenv" function, to work with various implementations was created the "my-getenv" function.
(defun my-getenv (name &optional default)
#+CMU
(let ((x (assoc name ext:*environment-list*
:test #'string=)))
(if x (cdr x) default))
#-CMU
(or
#+Allegro (sys:getenv name)
#+CLISP (ext:getenv name)
#+ECL (si:getenv name)
#+SBCL (sb-unix::posix-getenv name)
#+ABCL (getenv name)
#+LISPWORKS (lispworks:environment-variable name)
default))
(if (not ( null (remove-if #'null (mapcar #'my-getenv '("LANG" "LC_ALL" "LC_CTYPE")))))
(format t "Unicode is supported on this terminal and U+25B3 is : ~a~&" (code-char #x25b3))
(format t "Unicode is not supported on this terminal.~&")
)
- Output:
Unicode is supported on this terminal and U+25B3 is : △
Elixir
if ["LANG", "LC_CTYPE", "LC_ALL"]
|> Enum.map(&System.get_env/1)
|> Enum.any?(&(&1 != nil and String.contains?(&1, "UTF")))
do
IO.puts "This terminal supports Unicode: \x{25b3}"
else
raise "This terminal does not support Unicode."
end
FreeBASIC
Print "Terminal handle unicode and U+25B3 is: "; WChr(&H25B3)
FunL
if map( v -> System.getenv(v), ["LC_ALL", "LC_CTYPE", "LANG"]).filter( (!= null) ).exists( ('UTF' in) )
println( '\u25b3' )
else
println( 'Unicode not supported' )
Go
package main
import (
"fmt"
"os"
"strings"
)
func main() {
lang := strings.ToUpper(os.Getenv("LANG"))
if strings.Contains(lang, "UTF") {
fmt.Printf("This terminal supports unicode and U+25b3 is : %c\n", '\u25b3')
} else {
fmt.Println("This terminal does not support unicode")
}
}
- Output:
This terminal supports unicode and U+25b3 is : △
Haskell
import System.Environment
import Data.List
import Data.Char
import Data.Maybe
main = do
x <- mapM lookupEnv ["LANG", "LC_ALL", "LC_CTYPE"]
if any (isInfixOf "UTF". map toUpper) $ catMaybes x
then putStrLn "UTF supported: \x25b3"
else putStrLn "UTF not supported"
Output:
UTF supported: △
jq
The jq "env" function is required to inspect environment variables. It is NOT available in jq version 1.4.
Note also that "The values of locale categories are determined by a precedence order ..." -- http://pubs.opengroup.org/onlinepubs/007908799/xbd/envvar.html
"has_unicode_support" therefore cannot simply test whether one of the variables LC_ALL, LC_TYPE and LANG contains the string UTF.
def has_unicode_support:
def utf: if . == null then false else contains("UTF") or contains("utf") end;
env.LC_ALL
| if utf then true
elif . != null and . != "" then false
elif env.LC_CTYPE | utf then true
else env.LANG | utf
end ;
def task:
if has_unicode_support then "\u25b3"
else error("HW65001 This program requires a Unicode-compatible terminal")
end ;
task
- Output:
$ jq -M -r -n -f Terminal_control.jq jq: error: HW65001 This program requires a Unicode-compatible terminal
# In a galaxy not far away: $ jq -M -r -n -f Terminal_control.jq △
Jsish
Detection based on code from other entries, looking in LC_ALL, LC_CTYPE, LANG for hints of 'UTF'.
/* Terminal Control/Unicode, in Jsish */
var utf = false;
for (var envar of ['LC_ALL', 'LC_CTYPE', 'LANG']) {
var val = Util.getenv(envar);
if (val && (val.search(/utf/i) > 0)) {
utf = true;
break;
}
}
puts((utf) ? '\u25b3' : 'Unicode support not detected');
/*
=!EXPECTSTART!=
△
=!EXPECTEND!=
*/
- Output:
prompt$ jsish --U terminalControlUnicode.jsi △
Julia
c = '\u25b3'
if ismatch(r"UTF", get(ENV, "LANG", ""))
println("This output device supports Unicode: ", c)
else
println("This output device does not support Unicode.")
end
- Output:
This output device supports Unicode: △
Kotlin
// version 1.1.2
fun main(args: Array<String>) {
val supportsUnicode = "UTF" in System.getenv("LANG").toUpperCase()
if (supportsUnicode)
println("This terminal supports unicode and U+25b3 is : \u25b3")
else
println("This terminal does not support unicode")
}
- Output:
This terminal supports unicode and U+25b3 is : △
Lasso
local(env_vars = sys_environ -> join('###'))
if(#env_vars >> regexp(`(LANG|LC_ALL|LC_CTYPE).*?UTF.*?###`)) => {
stdout('UTF supported \u25b3')
else
stdout('This terminal does not support UTF')
}
UTF supported △
M2000 Interpreter
M2000 Environment has own console (with graphics support)
Module CheckIt {
If IsWine then Font "DejaVu Sans"
Cls
Report format$("\u25B3")
Keyboard 0x25B3, format$("\u25B3")
\\ report use kerning
Report Key$+"T"+Key$
Keyboard 0x25B3, format$("\u25B3")
Print Key$;"T";Key$
}
Checkit
Mathematica /Wolfram Language
If[StringMatchQ[$CharacterEncoding, "UTF*"], Print[FromCharacterCode[30000]], Print["UTF-8 capable terminal required"]]
->田
Mercury
:- module unicode_output.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
:- import_module list.
:- import_module maybe.
:- import_module string.
main(!IO) :-
list.map_foldl(io.get_environment_var, ["LANG", "LC_ALL", "LC_CTYPE"], EnvValues, !IO),
( if
list.member(EnvValue, EnvValues),
EnvValue = yes(Lang),
string.sub_string_search(Lang, "UTF-8", _)
then
io.write_string("Unicode is supported on this terminal and U+25B3 is : \u25b3\n", !IO)
else
io.write_string("Unicode is not supported on this terminal.\n", !IO)
).
Output:
Unicode is supported on this terminal and U+25B3 is : △
Nemerle
Typically, on a windows system, the output encoding is not UTF-8, so in an actual application it would make more sense to set Console.OutputEncoding than to merely check it.
using System.Console;
module UnicodeOut
{
Main() : void
{
if (OutputEncoding.ToString() == "System.Text.UTF8Encoding") Write("Δ")
else Write("Console encoding may not support Unicode characters.");
}
}
Nim
import os, strutils
if "utf" in getEnv("LANG").toLower:
echo "Unicode is supported on this terminal and U+25B3 is: △"
else:
echo "Unicode is not supported on this terminal."
Perl
Much like Raku...
die "Terminal can't handle UTF-8"
unless $ENV{LC_ALL} =~ /utf-8/i or $ENV{LC_CTYPE} =~ /utf-8/i or $ENV{LANG} =~ /utf-8/i;
print "△ \n";
Phix
Works on both linux and windows.
The following (grubby low-level details are hidden away in) builtins/unicode_console.e which is now included in the standard distribution:
with javascript_semantics include builtins\cffi.e constant tGSH = """ HANDLE WINAPI GetStdHandle( _In_ DWORD nStdHandle ); """, tSCOCP = """ BOOL WINAPI SetConsoleOutputCP( _In_ UINT wCodePageID ); """, STD_OUTPUT_HANDLE = -11, CP_UTF8 = 65001, envset = {"LANG","LC_ALL","LC_CTYPE"} atom k32 = NULL, xGetStdHandle, hConsole, xSetConsoleOutputCP global function unicode_console() -- initialises the windows console for unicode, and -- returns true if unicode is supported, else false. bool res = false if platform()=WINDOWS then if k32=NULL then puts(1,"") -- force console to exist k32 = open_dll("kernel32.dll") xGetStdHandle = define_cffi_func(k32,tGSH) hConsole = c_func(xGetStdHandle,{STD_OUTPUT_HANDLE}) xSetConsoleOutputCP = define_cffi_func(k32,tSCOCP) end if -- following is equivalent to running "chcp 65001": res = c_func(xSetConsoleOutputCP,{CP_UTF8}) else -- LINUX for i=1 to length(envset) do if match("UTF",upper(getenv(envset[i])))!=0 then res = true exit end if end for end if return res end function
Which can be used like this:
with javascript_semantics include builtins\unicode_console.e -- pi, root, lambda, sigma, delta constant prlsd = "\u03C0\u221A\u03BB\u03A3\u25B3" if unicode_console() then puts(1,prlsd&"\n") else puts(1,"unicode is not supported\n") end if
Note that delta does not work on Windows (see talk page) but the others do, and all five work on linux and under pwa/p2js.
PicoLisp
(if (sub? "UTF-8" (or (sys "LC_ALL") (sys "LC_CTYPE") (sys "LANG")))
(prinl (char (hex "25b3")))
(quit "UTF-8 capable terminal required") )
Python
import sys
if "UTF-8" in sys.stdout.encoding:
print("△")
else:
raise Exception("Terminal can't handle UTF-8")
R
if (any(grepl("UTF", toupper(Sys.getenv(c("LANG", "LC_ALL", "LC_CTYPE")))))) {
cat("Unicode is supported on this terminal and U+25B3 is : \u25b3\n")
} else {
cat("Unicode is not supported on this terminal.")
}
- Output:
Unicode is supported on this terminal and U+25B3 is : △
Racket
#lang racket
(displayln
(if (regexp-match? #px"(?i:utf-?8)"
(or (getenv "LC_ALL") (getenv "LC_CTYPE") (getenv "LANG")))
"\u25b3" "No Unicode detected."))
Raku
(formerly Perl 6)
die "Terminal can't handle UTF-8"
unless first(*.defined, %*ENV<LC_ALL LC_CTYPE LANG>) ~~ /:i 'utf-8'/;
say "△";
- Output:
△
Ruby
#encoding: UTF-8 # superfluous in Ruby >1.9.3
if ENV.values_at("LC_ALL","LC_CTYPE","LANG").compact.first.include?("UTF-8")
puts "△"
else
raise "Terminal can't handle UTF-8"
end
Scala
Ad hoc in the REPL:
scala> println(s"Unicode is supported on this terminal and U+25B3 is : \u25b3")
Unicode is supported on this terminal and U+25B3 is : △
Seed7
The Seed7 library console.s7i defines STD_CONSOLE, which can used directly, or be assigned to OUT (which is the default output file). STD_CONSOLE supports Unicode under Linux and Windows.
$ include "seed7_05.s7i";
include "environment.s7i";
include "console.s7i";
const proc: main is func
begin
if pos(lower(getenv("LANG")), "utf") <> 0 or
pos(lower(getenv("LC_ALL")), "utf") <> 0 or
pos(lower(getenv("LC_CTYPE")), "utf") <> 0 then
writeln(STD_CONSOLE, "Unicode is supported on this terminal and U+25B3 is: △");
else
writeln("Unicode is not supported on this terminal.");
end if;
end func;
Sidef
if (/\bUTF-?8/i ~~ [ENV{"LC_ALL","LC_CTYPE","LANG"}]) {
say "△"
} else {
die "Terminal can't handle UTF-8.\n";
}
Tcl
Tcl configures the standard output channel to use the system encoding by default. The system encoding is formally the encoding for use when communicating with the OS (e.g., for filenames) but is virtually always correlated with the default terminal encoding.
# Check if we're using one of the UTF or "unicode" encodings
if {[string match utf-* [encoding system]] || [string match *unicode* [encoding system]]} {
puts "\u25b3"
} else {
error "terminal does not support unicode (probably)"
}
Note that idiomatic Tcl code would not perform such a check; it would just produce the output which would be translated as best as possible (possibly into the target encoding's placeholder character).
UNIX Shell
This script only checks if the name of the locale contains "UTF-8". This often works because many UTF-8 locales have names like "en_US.UTF-8". This script will fail to recognize a Unicode terminal if:
- The locale is a UTF-8 locale, but does not have "UTF-8" in its name.
- The locale uses some other Unicode Transformation Format, such as GB18030.
unicode_tty() {
# LC_ALL supersedes LC_CTYPE, which supersedes LANG.
# Set $1 to environment value.
case y in
${LC_ALL:+y}) set -- "$LC_ALL";;
${LC_CTYPE:+y}) set -- "$LC_CTYPE";;
${LANG:+y}) set -- "$LANG";;
y) return 1;; # Assume "C" locale not UTF-8.
esac
# We use 'case' to perform pattern matching against a string.
case "$1" in
*UTF-8*) return 0;;
*) return 1;;
esac
}
if unicode_tty; then
# printf might not know \u or \x, so use octal.
# U+25B3 => UTF-8 342 226 263
printf "\342\226\263\n"
else
echo "HW65001 This program requires a Unicode compatible terminal" >&2
exit 252 # Incompatible hardware
fi
The terminal might support UTF-8, but its fonts might not have every Unicode character. Unless they have U+25B3, the output will not look correct. Greek letters like U+25B3 tend to be common, but some fonts might not have Chinese characters (for example), and almost no fonts have dead scripts such as Cuneiform.
Wren
As there is currently no way to obtain this information via Wren CLI, we instead embed a Wren script in a C application and ask the host program to get it for us.
/* Terminal_control_Unicode_output.wren */
class C {
foreign static isUnicodeSupported
}
if (C.isUnicodeSupported) {
System.print("Unicode is supported on this terminal and U+25B3 is : \u25b3")
} else {
System.print("Unicode is not supported on this terminal.")
}
We now embed this Wren script in the following C program, compile and run it.
/* gcc Terminal_control_Unicode_output.c -o Terminal_control_Unicode_output -lwren -lm */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "wren.h"
void C_isUnicodeSupported(WrenVM* vm) {
char *str = getenv("LANG");
bool us = false;
int i;
for (i = 0; str[i + 2] != 0; i++) {
if ((str[i] == 'u' && str[i + 1] == 't' && str[i + 2] == 'f') ||
(str[i] == 'U' && str[i + 1] == 'T' && str[i + 2] == 'F')) {
us = true;
break;
}
}
wrenSetSlotBool(vm, 0, us);
}
WrenForeignMethodFn bindForeignMethod(
WrenVM* vm,
const char* module,
const char* className,
bool isStatic,
const char* signature) {
if (strcmp(module, "main") == 0) {
if (strcmp(className, "C") == 0) {
if (isStatic && strcmp(signature, "isUnicodeSupported") == 0) {
return C_isUnicodeSupported;
}
}
}
return NULL;
}
static void writeFn(WrenVM* vm, const char* text) {
printf("%s", text);
}
void errorFn(WrenVM* vm, WrenErrorType errorType, const char* module, const int line, const char* msg) {
switch (errorType) {
case WREN_ERROR_COMPILE:
printf("[%s line %d] [Error] %s\n", module, line, msg);
break;
case WREN_ERROR_STACK_TRACE:
printf("[%s line %d] in %s\n", module, line, msg);
break;
case WREN_ERROR_RUNTIME:
printf("[Runtime Error] %s\n", msg);
break;
}
}
char *readFile(const char *fileName) {
FILE *f = fopen(fileName, "r");
fseek(f, 0, SEEK_END);
long fsize = ftell(f);
rewind(f);
char *script = malloc(fsize + 1);
fread(script, 1, fsize, f);
fclose(f);
script[fsize] = 0;
return script;
}
int main() {
WrenConfiguration config;
wrenInitConfiguration(&config);
config.writeFn = &writeFn;
config.errorFn = &errorFn;
config.bindForeignMethodFn = &bindForeignMethod;
WrenVM* vm = wrenNewVM(&config);
const char* module = "main";
const char* fileName = "Terminal_control_Unicode_output.wren";
char *script = readFile(fileName);
WrenInterpretResult result = wrenInterpret(vm, module, script);
switch (result) {
case WREN_RESULT_COMPILE_ERROR:
printf("Compile Error!\n");
break;
case WREN_RESULT_RUNTIME_ERROR:
printf("Runtime Error!\n");
break;
case WREN_RESULT_SUCCESS:
break;
}
wrenFreeVM(vm);
free(script);
return 0;
}
- Output:
Unicode is supported on this terminal and U+25B3 is : △
zkl
This code works for Unix/Linux, Windows XP cmd terminals don't support UTF-8.
if(System.isUnix and T("LC_CTYPE","LC_LANG","LANG").apply(System.getenv)
.filter().filter("holds","UTF"))
println("This terminal supports UTF-8 (\U25B3;)");
else println("I have doubts about UTF-8 on this terminal.");
- Output:
This terminal supports UTF-8 (△)
ZX Spectrum Basic
10 REM There is no Unicode delta in ROM
20 REM So we first define a custom character
30 FOR l=0 TO 7
40 READ n
50 POKE USR "d"+l,n
60 NEXT l
70 REM our custom character is a user defined d
80 PRINT CHR$(147): REM this outputs our delta
9500 REM data for our custom delta
9510 DATA 0,0,8,20,34,65,127,0