Does `std::vector` Copy Objects When Using `push_back()`?

Does std::vector Copy Objects When Appending Using push_back?

After meticulous investigation using Valgrind, some users have reached the conclusion that std::vector creates copies of objects pushed into the container using the push_back() method. This has raised questions about the vector's ability to hold references or pointers without making copies.

std::vector Behavior

The assumption is correct. When an object is pushed_back() into a std::vector, a copy of that object is made and stored within the vector. This is due to the fact that std::vector internally manages an array of objects of type T, and any changes to the vector's elements must be reflected in the vector itself.

Alternatives for Storing References or Pointers

If you intend to store references or pointers to objects in your vector, the solution is to use a std::vector instead of std::vector. This allows you to store references or pointers directly, without copying the referenced objects.

Maintaining Object Validity

When using a std::vector, it is important to ensure that the objects referenced by the pointers remain valid throughout the vector's lifespan (until they are removed using erase() or until the vector is destroyed). Smart pointers that utilize the Resource Acquisition Is Initialization (RAII) idiom can assist in managing object lifetimes, ensuring proper cleanup when the object is no longer referenced by the vector.

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