Std::iswdigit (3) Linux Manual Page

std::iswdigit – std::iswdigit

Synopsis

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.
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 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
// 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

                     checks if a character is classified as a digit by a locale
isdigit(std::locale) (function template)
                     checks if a character is a digit
isdigit (function)
ASCII values iscntrl isprint isspace isblank isgraph ispunct isalnum isalpha isupper islower isdigit isxdigit
decimal hexadecimal octal characters iswcntrl iswprint iswspace iswblank iswgraph iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit
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–\10ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0
71–90 \x47–\x5A \107–\13GHIJKLMNOP 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
                              QRSTUVWXYZ
91–96 \x5B–\x60 \133–\14[\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
97–102\x61–\x66 \141–\14abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0
103–12\x67–\x7A \147–\17ghijklmnop 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
                              qrstuvwxyz
123–12\x7B–\x7E \172–\17{|}~ 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

std::iswdigit (3) Linux Manual Page