std::function<R(Args...)>::operator bool
explicit operator bool() const noexcept; |
(since C++11) |
Checks whether *this
stores a callable function target, i.e. is not empty.
Parameters
(none).
Return value
true
if *this
stores a callable function target, false
otherwise.
Example
#include <functional> #include <iostream> void sampleFunction() { std::cout << "This is the sample function!\n"; } void checkFunc( std::function<void()> 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::function<void()> f1; std::function<void()> f2( sampleFunction ); std::cout << "f1: "; checkFunc( f1 ); std::cout << "f2: "; checkFunc( f2 ); }
Output:
f1: Function is empty. Nothing to do. f2: Function is not empty! Calling function. This is the sample function!
See also
(C++23)
|
checks if the std::move_only_function has a target (public member function of std::move_only_function<R(Args...) cv ref noexcept(noex)> ) |
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