template< class... Args >
void emplace( Args&&... args );
(since C++11)
(until C++17)
template< class... Args >
decltype(auto) emplace( Args&&... args );
(since C++17)

Pushes a new element on top of the stack. The element is constructed in-place, i.e. no copy or move operations are performed. The constructor of the element is called with exactly the same arguments as supplied to the function.

Effectively calls c.emplace_back(std::forward<Args>(args)...);


args - arguments to forward to the constructor of the element

Return value

(none) (until C++17)
The value or reference, if any, returned by the above call to Container::emplace_back. (since C++17)


Identical to the complexity of Container::emplace_back.


#include <iostream>
#include <stack>
struct S
    int id;
    S(int i, double d, std::string s) : id{i}
        std::cout << "S::S(" << i << ", " << d << ", \"" << s << "\");\n";
int main()
    std::stack<S> adaptor;
    const S& s = adaptor.emplace(42, 3.14, "C++"); // for return value C++17 required
    std::cout << "id = " << s.id << '\n';


S::S(42, 3.14, "C++")
id = 42

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 2783 C++17 emplace returned reference, breaking compatibility with pre-C++17 containers returns decltype(auto)

See also

inserts element at the top
(public member function)
removes the top element
(public member function)

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