`push_back` vs. `emplace_back`: When Should You Use Which?

push_back vs emplace_back

In understanding the differences between push_back and emplace_back, it's crucial to grasp the distinction between the various overloads for push_back.

push_back Overloads

push_back offers three overloads handling different data types and references:

• push_back(const Type& _Val): Receives a copy of the provided data type.
• push_back(Type& _Val): Handles a reference to the actual data type.
• push_back(Type&& _Val): Accepts a rvalue reference to the data type.

emplace_back Overload in MSVC10

In Microsoft Visual C 10 (MSVC10), emplace_back has an additional overload:

• emplace_back(Type&&& _Val): This overload is essentially redundant and has no unique functionality compared to the push_back(Type&& _Val) overload.

C 0x's emplace_back Overload

The genuine C 0x definition of emplace_back differs significantly:

• emplace_back(Args&&&...): This overload enables the container to construct an object directly within itself using a variadic list of arguments.

Advantages of emplace_back in C 0x

The C 0x version of emplace_back offers several advantages:

• Direct Object Construction: It directly constructs an object within the container without creating a temporary object first.
• Faster Performance: This method bypasses potential copies and moves, which is particularly beneficial in complex scenarios where push_back might introduce unnecessary copies or moves.

Conclusion

In C , emplace_back is a powerful addition to the push_back function that enables straightforward construction of objects within a container using a variadic list of arguments. While MSVC10 offers a non-conforming implementation of emplace_back, the genuine C 0x implementation provides significant performance benefits and allows for more efficient construction of objects within containers.

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