来到C++17后,就可以使用if-constexpr了: template<typenameT>std::stringtoStr(Tt){ifconstexpr(std::is_same_v<T,std::string>)returnt;elsereturnstd::to_string(t);} 代码的可读性与上面使用enable_if相比好了许多! 本文主要参考了下面两篇文章: An introduction to C++'s SFINAE concept: compile-time...
Cloud Studio代码运行 consteval boolcheckStringLength(conststd::string&str,uint maxLength){if(str.length()>maxLength){returnfalse;}returntrue;}intmain(){,constexpr int maxLength=10;if(checkStringLength("Hello,world",maxLength)){std::cout<<"字符串长度在正常范围内."<<std::endl;}return0;} 如...
例如:concept meowable = requires (T obj) { 概念会帮助类型特征在模板元编程<em 浏览0提问于2021-06-02得票数 12 1回答 非常数常量表达式成员函数的用法? 、、、 在C++14及更高版本中,用于成员函数的constexpr不再意味着const。struct Value int i = 5; {discards qualifiers [-fpermissive] ^ 似乎在编...
template <typename T> concept numeric = std::is_integral_v<T> || std::is_floating_point_v<T>; And use it:template <typename T> requires numeric<T> constexpr double Average2(std::vector<T> const &vec) { const double sum = std::accumulate(vec.begin(), vec.end(), 0.0); ...
; template < class... TTypes > class C { private: template<typename TToMatch> static constexpr bool c_fVariantTypesContain = OneOfTheseTypes<TToMatch, TTypes...>; public: void F() const noexcept requires(c_fVariantTypesContain<int> || c_fVariantTypesContain<long long>)...
Basically - the lambda gives you a place where you canif constexpron that constraint. But the lambda can't return atype, it can only return a value - so we instead return some kind ofstd::type_identity<T>. And then we need todecltype(...)::typeto actually pull theTout. ...
<cpp |keyword C++ ifstatement: begins theifstatement constexprifstatement: begins theconstexprifstatement (since C++17) constevalifstatement: begins theconstevalifstatement (since C++23) See also ifstatement:else constexprifstatement:constexpr(constexprifstatement) ...
If it's VS generated lib or dll then it simply follow Guido suggestion , if it is generated by you then also you can use same concept which will help you . If this is third party then it is very hard to tell because you can add "D" on a release build as well and you c...
> loop directly), we can make the _Iter_equals_val case of __find_if call > std::find, to take advantage of its memchr optimization. This benefits > other algos like search_n which use __find_if with _Iter_equals_val.
如果您只想为不同的类型运行一两行不同的代码，那么constexpr if可以让您不必使用enable_if就可以做到...