iswdigit

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

Checks if the given wide character corresponds (if narrowed) to one of the ten decimal digit characters 0123456789.

Parameters

ch

-

wide character

Return value

Non-zero value if the wide character is an 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

Run this code

#include <stdio.h>
#include <wctype.h>
#include <wchar.h>
#include <locale.h>

void test(wchar_t a3, wchar_t u3, wchar_t j3)
{
    printf("        '%lc' '%lc' '%lc'\n", a3, u3, j3);
    printf("iswdigit%d   %d  %d\n",
           !!iswdigit(a3), !!iswdigit(u3), !!iswdigit(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'3';  // the ASCII digit 3
    wchar_t u3 = L''; // the CJK numeral 3
    wchar_t j3 = L''; // the fullwidth digit 3

    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);
}

Output:

In American locale:
        '3' '' ''
iswdigit 1    0   0
jdigit:  0    0   0

In Japanese locale:
        '3' '' ''
iswdigit 1    0   0
jdigit:  0    0   1

References

C11 standard (ISO/IEC 9899:2011):

7.30.2.1.5 The iswdigit function (p: 449)

C99 standard (ISO/IEC 9899:1999):

7.25.2.1.5 The iswdigit function (p: 395)

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	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`
08	`\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`
1013	`\xA\xD`	`\12\15`	whitespaces (`\n`, `\v`, `\f`, `\r`)	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
1431	`\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`
3347	`\x21\x2F`	`\41\57`	`!"#$%&'()*+,-./`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
4857	`\x30\x39`	`\60\71`	`0123456789`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
5864	`\x3A\x40`	`\72\100`	`:;<=>?@`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
6570	`\x41\x46`	`\101\106`	`ABCDEF`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
7190	`\x47\x5A`	`\107\132`	`GHIJKLMNOP` `QRSTUVWXYZ`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
9196	`\x5B\x60`	`\133\140`	[\]^_`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
97102	`\x61\x66`	`\141\146`	`abcdef`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
103122	`\x67\x7A`	`\147\172`	`ghijklmnop` `qrstuvwxyz`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`	`0`
123126	`\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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