std::iswdigit
From cppreference.com
| Defined in header <cwctype>
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int iswdigit( wint_t ch );
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Checks if the given wide character corresponds (if narrowed) to one of the ten decimal digit characters 0123456789.
If the value of ch is neither representable as a wchar_t nor equal to the value of the macro WEOF, the behavior is undefined.
Parameters
| ch | - | wide character |
Return value
Non-zero value if the wide character is a 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
Run this code
#include <clocale>
#include <cwctype>
#include <iostream>
void test(wchar_t a3, wchar_t u3, wchar_t j3)
{
std::wcout << std::boolalpha
<< "\t '" << 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''; // the CJK numeral 3
wchar_t j3 = L''; // the full-width 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);
}
Possible output:
In American locale:
'3' '' ''
iswdigit: true false false
jdigit: false false false
In Japanese locale:
'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 | characters | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| decimal | hexadecimal | octal | |||||||||||||
| 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
|
GHIJKLMNOPQRSTUVWXYZ
|
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
|
ghijklmnopqrstuvwxyz
|
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
|