std::swap(std::function)
Defined in header <functional> |
||
|---|---|---|
|
(since C++11) |
Overloads the std::swap algorithm for std::function. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).
Parameters
| lhs, rhs | - | polymorphic function wrappers whose states to swap |
Return value
(none)
Example
#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 << "std::swap(f1, f2);\n";
std::swap(f1, f2);
f1("f1", 1);
f2("f2", 2);
}Output:
foo("f1", 1)
bar("f2", 2)
std::swap(f1, f2);
bar("f1", 1)
foo("f2", 2)Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2062 | C++11 | overload of swap for function was not required to be noexcept |
required |
See also
| swaps the contents (public member function) |
|
|
(C++23)
|
overloads the std::swap algorithm (function) |
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