C++ Functional Library - operator()

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Description

It invokes the stored callable function target with the parameters args.

Declaration

Following is the declaration for std::function::function::operator()

 R operator()( Args... args ) const; 

C++11

 R operator()( Args... args ) const; 

Parameters

args − parameters to pass to the stored callable function target.

Return Value

It returns none if R is void. Otherwise the return value of the invocation of the stored callable object.

Exceptions

noexcept: It doesnot throw any exceptions.

Example

In below example for std::function::operator().

 #include <iostream> #include <functional> void call(std::function<int()> f) { std::cout << f() << '\n'; } int normal_function() { return 50; } int main() { int n = 4; std::function<int()> f = [&n](){ return n; }; call(f); n = 5; call(f); f = normal_function; call(f); } 

The output should be like this −

 4 5 50