std::iswdigit

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Text processing library

Localization library

Regular expressions library(C++11)

Formatting library(C++20)

Null-terminated sequence utilities

Byte strings

Multibyte strings

Wide strings

Primitive numeric conversions

to_chars (C++17) to_chars_result (C++17) from_chars (C++17) from_chars_result (C++17) chars_format (C++17)

Text encoding identifications

text_encoding (C++26)

 

Null-terminated wide strings

Functions
Character classification
iswalnum iswalpha iswlower iswupper iswdigit iswxdigit wctype	iswblank (C++11) iswctype iswcntrl iswgraph iswspace iswprint iswpunct
Character manipulation
towlower towupper	towctrans wctrans
Conversions to numeric formats
wcstolwcstoll (C++11)   wcstofwcstodwcstold (C++11)(C++11)	wcstoulwcstoull (C++11) wcstoimaxwcstouimax (C++11)(C++11)
String manipulation
wcslen wcscmp wcscoll wcsncmp wcschr wcsrchr	wcspbrk wcsspn wcscspn wcsstr wcstok
String examination
wcscpy wcsncpy wcsxfrm	wcscat wcsncat
Array manipulation
wmemcpy wmemmove wmemcmp	wmemchr wmemset
Types wctrans_t wctype_t wint_t	Macros WCHAR_MIN WCHAR_MAX WEOF

 

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 3wchar_t u3 = L'三';// the CJK numeral 3wchar_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 iswcntrl	isprint iswprint	isspace iswspace	isblank iswblank	isgraph iswgraph	ispunct iswpunct	isalnum iswalnum	isalpha iswalpha	isupper iswupper	islower iswlower	isdigit iswdigit	isxdigit iswxdigit
decimal	hexadecimal	octal
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–\106	ABCDEF	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	≠0
71–90	\x47–\x5A	\107–\132	GHIJKLMNOP QRSTUVWXYZ	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	0
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 qrstuvwxyz	0	≠0	0	0	≠0	0	≠0	≠0	0	≠0	0	0
123–126	\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