std::move_only_function<R(Args...) cv ref noexcept(noex)>::operator bool
来自cppreference.com
< cpp | utility | functional | move only function
explicit operator bool() const noexcept; |
(C++23 起) | |
检查 *this 是否存储可调用目标,即非空。
参数
(none)
返回值
若 *this 存储可调用目标则为 true ,否则为 false 。
示例
运行此代码
#include <functional> #include <iostream> void sampleFunction() { std::cout << "This is the sample function!\n"; } void checkFunc( std::move_only_function<void() const> const &func ) { // Use operator bool to determine if callable target is available. if( func ) { std::cout << "Function is not empty! Calling function.\n"; func(); } else { std::cout << "Function is empty. Nothing to do.\n"; } } int main() { std::move_only_function<void() const> f1{}; std::move_only_function<void() const> f2{ sampleFunction }; std::cout << "f1: "; checkFunc(f1); std::cout << "f2: "; checkFunc(f2); }
输出:
f1: Function is empty. Nothing to do. f2: Function is not empty! Calling function. This is the sample function!
参阅
检查是否包含了有效的目标 ( std::function<R(Args...)> 的公开成员函数) |