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 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

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)

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)