| 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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| Member functions | ||||
ctype::isctype::do_is | ||||
| Member functions of ctype<char> | ||||
Defined in header <locale> | ||
public: bool is( mask m, CharT c)const; | (1) | |
public: const CharT* is(const CharT* low,const CharT* high, mask* vec)const; | (2) | |
protected: virtualbool do_is( mask m, CharT c)const; | (3) | |
protected: virtualconst CharT* do_is(const CharT* low,const CharT* high, mask* vec)const; | (4) | |
do_is of the most derived class.[low, high), identifies the complete classification mask (e.g.digit|xdigit|alnum|print|graph for the digit'0' in the default locale), and stores the masks in the corresponding elements of the array pointed to byvec.Contents |
| c | - | character to classify |
| m | - | mask to use for classifying a single character |
| low | - | pointer to the first character in an array of characters to classify |
| high | - | one past the end pointer for the array of characters to classify |
| vec | - | pointer to the first element of the array of masks to fill |
#include <cstddef>#include <iostream>#include <locale>#include <utility>#include <vector> // utility wrapper to make locale-bound facets destructibletemplate<class Facet>struct deletable_facet: Facet{template<class ...Args> deletable_facet(Args&& ...args): Facet(std::forward<Args>(args)...){} ~deletable_facet(){}}; int main(){// classify a single character using the default localeauto& f=std::use_facet<std::ctype<char>>(std::locale());char c='0';if(f.is(std::ctype_base::digit, c))// or isdigit(c, locale());std::cout<<'\''<< c<<"' is a digit\n"; // classify every character in a string using a named locale deletable_facet<std::ctype_byname<wchar_t>> f2("en_US.utf8");std::wstring str= L"z\u00df\u6c34\U0001d10b";std::vector<std::ctype_base::mask> vec(str.size()); f2.is(&str[0],&str[0]+ str.size(),&vec[0]); for(std::size_t n=0; n< str.size();++n){std::cout<<std::hex<<"U+"<<static_cast<wint_t>(str[n])<<" is: ";if(vec[n]&std::ctype_base::alnum)std::cout<<"alnum";if(vec[n]&std::ctype_base::punct)std::cout<<"punct";std::cout<<'\n';}}
Output:
'0' is a digitU+7a is: alnum U+df is: alnum U+6c34 is: alnum U+1d10b is: punct
| classifies a character or a character sequence, using the classification table (public member function of std::ctype<char>)[edit] | |
classifies a wide character according to the specifiedLC_CTYPE category(function)[edit] |
