std::iswdigit(3)

NAME
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 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'三'; // the CJK numeral 3
     wchar_t j3 = L'３'; // 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' '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
   isdigit(std::locale) checks if a character is classified as a digit by a locale
                        (function template)
   isdigit checks if a character is a digit
                        (function)
   C documentation for
   iswdigit
        ASCII values characters iscntrl isprint isspace isblank isgraph ispunct isalnum isalpha isupper islower isdigit isxdigit decimal hexadecimal octal iswcntrl iswprint iswspace iswblank iswgraph iswpunct iswalnum iswalpha iswupper iswlower iswdigit iswxdigit 0–8 \x0–\x8 \0–\10 control codes ≠0 0 0 0 0 0 0 0 0 0 0 0
                        (NUL, etc.) 9 \x9 \11 tab (\t) ≠0 0 ≠0 ≠0 0 0 0 0 0 0 0 0
                        whitespaces 10–13 \xA–\xD \12–\15 (\n, \v, \f, ≠0 0 ≠0 0 0 0 0 0 0 0 0 0
                        \r) 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–\106 ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0 71–90 \x47–\x5A \107–\132 GHIJKLMNOP 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
                        QRSTUVWXYZ 91–96 \x5B–\x60 \133–\140 [\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 97–102 \x61–\x66 \141–\146 abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0 103–122 \x67–\x7A \147–\172 ghijklmnop 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
                        qrstuvwxyz 123–126 \x7B–\x7E \172–\176 {|}~ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0 127 \x7F \177 backspace ≠0 0 0 0 0 0 0 0 0 0 0 0
                        character (DEL)