std::vector is probably the most commonly used container type, and for good reason. A vector is an array that grows dynamically when needed. The elements added to a vector are guaranteed to be laid out contiguously in memory, which means that you can access any element in the array by its index in constant time. It also means that it provides excellent performance when traversing the elements in the order they are laid out, thanks to the spatial locality mentioned earlier.
The vector has a size and a capacity. The size is the number of elements that are currently held in the container, and the capacity is the number of elements that the vector can hold until it needs to allocate more space:
Adding elements to the end of ...
