std::function<R(Args...)>:: swap

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
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( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
( until C++20* )
std::function
void swap ( function & other ) noexcept ;
(since C++11)

Exchanges the stored callable objects of * this and other .

Parameters

other - function wrapper to exchange the stored callable object with

Return value

(none)

Example

Run this code 
#include <functional>
#include <iostream>
 
void foo(const char* str, int x)
{
    std::cout << "foo(\"" << str << "\", " << x << ")\n";
}
 
void bar(const char* str, int x)
{
    std::cout << "bar(\"" << str << "\", " << x << ")\n";
}
 
int main()
{
    std::function<void(const char*, int)> f1{foo};
    std::function<void(const char*, int)> f2{bar};
 
    f1("f1", 1);
    f2("f2", 2);
 
    std::cout << "f1.swap(f2);\n";
    f1.swap(f2);
 
    f1("f1", 1);
    f2("f2", 2);
}

Output: 

foo("f1", 1)
bar("f2", 2)
f1.swap(f2);
bar("f1", 1)
foo("f2", 2)

See also

swaps the targets of two std::move_only_function objects
(public member function of std::move_only_function )
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