std::function::operator() - cppreference.com

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# std::function::operator()

From cppreference.com
< cpp‎ | utility‎ | functional‎ | function

R operator()( ArgTypes... args ) const; |  | (since C++11)

Calls the stored callable function target with the parameters `args`.

### [edit] Parameters

args | - | parameters to pass to the stored callable function target

### [edit] Return value

None if `R` is void. Otherwise the return value of the invocation of the stored callable object.

### [edit] Exceptions

- std::bad_function_call if *this does not store a callable function target, !*this == true.

### [edit] Example

The following example shows how std::function can passed to other functions by value. Also, it shown how std::function can store lambdas.

Run this code

    #include <iostream>
    #include <functional>

    void call(std::function<int()> f)  // can be passed by value
    {
        std::cout << f() << '\n';
    }

    int normal_function()
    {
        return 42;
    }

    int main()
    {
        int n = 1;
        std::function<int()> f = [&n](){ return n; };
        call(f);

        n = 2;
        call(f);

        f = normal_function;
        call(f);
    }

Output:

    1
    2
    42

### [edit] See also

| This section is incomplete

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