iswxdigit

Defined in header <wctype.h> 
int iswxdigit( wint_t ch );
 (since C95)

Checks if the given wide character corresponds (if narrowed) to a hexadecimal numeric character, i.e. one of 0123456789abcdefABCDEF.

Parameters

ch - wide character

Return value

Non-zero value if the wide character is a hexadecimal numeric character, zero otherwise.

Notes

iswdigit and iswxdigit are the only standard wide character classification functions that are not affected by the currently installed C locale.

Example

Some locales offer additional character classes that detect non-ASCII digits

#include <locale.h>
#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
 
void test(wchar_t a3, wchar_t u3, wchar_t j3)
{
    printf("\t  '%lc'  '%lc' '%lc'\n", a3, u3, j3);
    printf("iswxdigit: %d    %d    %d\n",
           !!iswxdigit(a3),
           !!iswxdigit(u3),
           !!iswxdigit(j3));
    printf("jdigit:    %d    %d    %d\n",
           !!iswctype(a3, wctype("jdigit")),
           !!iswctype(u3, wctype("jdigit")),
           !!iswctype(j3, wctype("jdigit")));
}
 
int main(void)
{
    wchar_t a3 = L'9';  // the ASCII digit 9
    wchar_t u3 = L'〩'; // the CJK numeral 9
    wchar_t j3 = L'９'; // the full-width digit 9
 
    setlocale(LC_ALL, "en_US.utf8");
    puts("In American locale:");
    test(a3, u3, j3);
 
    setlocale(LC_ALL, "ja_JP.utf8");
    puts("\nIn Japanese locale:");
    test(a3, u3, j3);
}

Possible output:

In American locale:
          '9'  '〩' '９'
iswxdigit: 1    0    0
jdigit:    0    0    0
 
In Japanese locale:
          '9'  '〩' '９'
iswxdigit: 1    0    0
jdigit:    0    0    1

References

  • C23 standard (ISO/IEC 9899:2023):
    • 7.30.2.1.12 The iswxdigit function (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
    • 7.30.2.1.12 The iswxdigit function (p: TBD)
  • C11 standard (ISO/IEC 9899:2011):
    • 7.30.2.1.12 The iswxdigit function (p: 451)
  • C99 standard (ISO/IEC 9899:1999):
    • 7.25.2.1.12 The iswxdigit function (p: 397)

See also

checks if a character is a hexadecimal character
(function)
C++ documentation for iswxdigit
ASCII values characters

iscntrl
iswcntrl

isprint
iswprint

isspace
iswspace

isblank
iswblank

isgraph
iswgraph

ispunct
iswpunct

isalnum
iswalnum

isalpha
iswalpha

isupper
iswupper

islower
iswlower

isdigit
iswdigit

isxdigit
iswxdigit
decimal hexadecimal octal
0–8 \x0–\x8 \0–\10 control codes (NUL, etc.) ≠0 0 0 0 0 0 0 0 0 0 0 0
9 \x9 \11 tab (\t) ≠0 0 ≠0 ≠0 0 0 0 0 0 0 0 0
10–13 \xA–\xD \12–\15 whitespaces (\n, \v, \f, \r) ≠0 0 ≠0 0 0 0 0 0 0 0 0 0
14–31 \xE–\x1F \16–\37 control codes ≠0 0 0 0 0 0 0 0 0 0 0 0
32 \x20 \40 space 0 ≠0 ≠0 ≠0 0 0 0 0 0 0 0 0
33–47 \x21–\x2F \41–\57 !"#$%&'()*+,-./ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
48–57 \x30–\x39 \60–\71 0123456789 0 ≠0 0 0 ≠0 0 ≠0 0 0 0 ≠0 ≠0
58–64 \x3A–\x40 \72–\100 :;<=>?@ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
65–70 \x41–\x46 \101–\106 ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0
71–90 \x47–\x5A \107–\132 GHIJKLMNOP
QRSTUVWXYZ 		0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
91–96 \x5B–\x60 \133–\140 [\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
97–102 \x61–\x66 \141–\146 abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0
103–122 \x67–\x7A \147–\172 ghijklmnop
qrstuvwxyz 		0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
123–126 \x7B–\x7E \172–\176 {|}~ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
127 \x7F \177 backspace character (DEL) ≠0 0 0 0 0 0 0 0 0 0 0 0

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