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std::iswdigit

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.

Parameters

ch - wide character

Return value

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

Notes

std::iswdigit and std::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 <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

See also

checks if a character is classified as a digit by a locale
(function template)
checks if a character is a digit
(function)
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
doc_CPP
doc_CPP
2025-01-10 15:47:30
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