| Localization library | |||||||||||||||||||||||||
| Regular expressions library(C++11) | |||||||||||||||||||||||||
| Formatting library(C++20) | |||||||||||||||||||||||||
| Null-terminated sequence utilities | |||||||||||||||||||||||||
| Byte strings | |||||||||||||||||||||||||
| Multibyte strings | |||||||||||||||||||||||||
| Wide strings | |||||||||||||||||||||||||
| Primitive numeric conversions | |||||||||||||||||||||||||
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| Text encoding identifications | |||||||||||||||||||||||||
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Defined in header <locale> | ||
template<class CharT> bool isdigit( CharT ch,const locale& loc); | ||
Checks if the given character is classified as a digit by the given locale'sstd::ctype facet.
Contents |
| ch | - | character |
| loc | - | locale |
Returnstrue if the character is classified as a digit,false otherwise.
template<class CharT>bool isdigit(CharT ch,conststd::locale& loc){returnstd::use_facet<std::ctype<CharT>>(loc).is(std::ctype_base::digit, ch);} |
#include <iostream>#include <locale>#include <string>#include <unordered_set> struct jdigit_ctype:std::ctype<wchar_t>{std::unordered_set<wchar_t> jdigits{ L'一', L'二', L'三', L'四', L'五', L'六', L'七', L'八', L'九', L'十'}; bool do_is(mask m, char_type c)const override{return(m& digit)&& jdigits.contains(c)?true// Japanese digits will be classified as digits: ctype::do_is(m, c);// leave the rest to the parent class}}; int main(){std::wstring text= L"123一二三１２３";std::locale loc(std::locale(""), new jdigit_ctype); std::locale::global(std::locale("en_US.utf8"));std::wcout.imbue(std::locale()); for(constwchar_t c: text)if(std::isdigit(c, loc))std::wcout<< c<<" is a digit\n";elsestd::wcout<< c<<" is NOT a digit\n";}
Possible output:
1 is a digit2 is a digit3 is a digit一 is a digit二 is a digit三 is a digit１ is NOT a digit２ is NOT a digit３ is NOT a digit
| checks if a character is a digit (function)[edit] | |
| checks if a wide character is a digit (function)[edit] |
