std::has_facet
Defined in header <locale> | | |
|---|---|---|
template< class Facet > bool has_facet( const locale& loc ); | | |
检查区域设置是否loc实现facetFacet...
参数
loc | - | the locale object to query |
|---|
返回值
回报true如果小面Facet已安装在区域设置中。loc，，，false否则。
例外
(none) | (until C++11) |
|---|---|
noexcept specification: noexcept | (since C++11) |
例
二次
#include <iostream>
#include <locale>
// minimal custom facet
struct myfacet : public std::locale::facet {
static std::locale::id id;
};
std::locale::id myfacet::id;
int main()
{
// loc is a "C" locale with myfacet added
std::locale loc(std::locale::classic(), new myfacet);
std::cout << std::boolalpha
<< "Can loc classify chars? "
<< std::has_facet<std::ctype<char>>(loc) << '\n'
<< "Can loc classify char32_t? "
<< std::has_facet<std::ctype<char32_t>>(loc) << '\n'
<< "Does loc implement myfacet? "
<< std::has_facet<myfacet>(loc) << '\n';
}二次
产出：
二次
Can loc classify chars? true
Can loc classify char32_t? false
Does loc implement myfacet? true二次
另见
locale | set of polymorphic facets that encapsulate cultural differences (class) |
|---|---|
use_facet | obtains a facet from a locale (function template) |
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