What is the capacity of C++ STL vectors?

Can you explain what the capacity of C++ STL vectors means?

Sure! The capacity of a C++ STL vector refers to the amount of space allocated for the vector's elements, which may be greater than or equal to its size.

How does the capacity change when I add elements to the vector?

When you add elements to a vector and its size exceeds its capacity, the vector automatically reallocates memory to accommodate the new elements, typically doubling its capacity.

Is there a way to reserve capacity in advance?

Yes, you can use the reserve() function to pre-allocate memory for a specific number of elements, which can improve performance by reducing the number of reallocations.

What happens if I call shrink_to_fit()?

The shrink_to_fit() function reduces the capacity of the vector to match its size, freeing any unused memory.