std::iswdigit - cppreference.com

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# std::iswdigit

From cppreference.com
< cpp‎ | string‎ | wide

Defined in header `<cwctype>` |  |
int iswdigit( wint_t ch ); |  |

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

### [edit] Parameters

ch | - | wide character

### [edit] Return value

Non-zero value (true) if the wide character is an numeric character, `0` (false) otherwise.

### [edit] Notes

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

### [edit] Example

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

Run this code

    #include <iostream>
    #include <cwctype>
    #include <clocale>
    void test(wchar_t a3, wchar_t u3, wchar_t j3)
    {
        std::wcout << std::boolalpha
                   << "          '" << a3 << "'   '" << u3 << "'  '" << j3  << "'\n"
                   << "iswdigit "
                   << (bool)std::iswdigit(a3) << "  "
                   << (bool)std::iswdigit(u3) << " "
                   << (bool)std::iswdigit(j3) << '\n'
                   << "jdigit:  "
                   << (bool)std::iswctype(a3, std::wctype("jdigit")) << ' '
                   << (bool)std::iswctype(u3, std::wctype("jdigit")) << ' '
                   << (bool)std::iswctype(j3, std::wctype("jdigit")) << '\n';
    }
    int main()
    {
        wchar_t a3 = L'3';  // the ASCII digit 3
        wchar_t u3 = L'三'; // the CJK numeral 3
        wchar_t j3 = L'３'; // the fullwidth digit 3

        std::setlocale(LC_ALL, "en_US.utf8");
        std::wcout << "In american locale:\n";
        test(a3, u3, j3);

        std::wcout << "\nIn japanese locale:\n";
        std::setlocale(LC_ALL, "ja_JP.utf8");
        test(a3, u3, j3);
    }

Output:

    In american locale:
              '3'   '三'  '３'
    iswdigit true  false false
    jdigit:  false false false

    In japanese locale:
              '3'   '三'  '３'
    iswdigit true  false false
    jdigit:  false false true

### [edit] See also

isdigit(std::locale) | checks if a character is classified as a digit by a locale (function template) [edit]
isdigit | checks if a character is a digit (function) [edit]
C documentation for iswdigit

ASCII values (hex) | 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`
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
0 - 8 | `0x00-0x08` | control codes (`NUL`, etc.) | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`
9 | `0x09` | tab (`\t`) | `≠0` | `0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`
10 - 13 | `0x0A-0x0D` | whitespaces (`\n`,`\v`,`\f`,`\r`) | `≠0` | `0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`
14 - 31 | `0x0E-0x1F` | control codes | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`
32 | `0x20` | space | `0` | `≠0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`
33 - 47 | `0x21-0x2F` | `!"#$%&'()*+,-./` | `0` | `≠0` | `0` | `0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0`
48 - 57 | `0x30-0x39` | `0123456789` | `0` | `≠0` | `0` | `0` | `≠0` | `0` | `≠0` | `0` | `0` | `0` | `≠0` | `≠0`
58 - 64 | `0x3a-0x40` | `:;<=>?@` | `0` | `≠0` | `0` | `0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0`
65 - 70 | `0x41-0x46` | `ABCDEF` | `0` | `≠0` | `0` | `0` | `≠0` | `0` | `≠0` | `≠0` | `≠0` | `0` | `0` | `≠0`
71 - 90 | `0x47-0x5A` | `GHIJKLMNOPQRSTUVWXYZ` | `0` | `≠0` | `0` | `0` | `≠0` | `0` | `≠0` | `≠0` | `≠0` | `0` | `0` | `0`
91 - 96 | `0x5B-0x60` | `[\]^_`` | `0` | `≠0` | `0` | `0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0`
97 -102 | `0x61-0x66` | `abcdef` | `0` | `≠0` | `0` | `0` | `≠0` | `0` | `≠0` | `≠0` | `0` | `≠0` | `0` | `≠0`
103-122 | `0x67-0x7A` | `ghijklmnopqrstuvwxyz` | `0` | `≠0` | `0` | `0` | `≠0` | `0` | `≠0` | `≠0` | `0` | `≠0` | `0` | `0`
123-126 | `0x7B-0x7E` | `{|}~` | `0` | `≠0` | `0` | `0` | `≠0` | `≠0` | `0` | `0` | `0` | `0` | `0` | `0`
127 | `0x7F` | backspace character (`DEL`) | `≠0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0` | `0`

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