`std::vector: resize() or reserve()? Which Method Should You Choose?`

Choice between vector::resize() and vector::reserve()

When allocating memory to a vector data member, there are two main methods to consider: vector::resize() and vector::reserve().

vector::resize()

The vector::resize() method inserts or deletes elements to adjust the size of the vector to the specified value. It affects both the size() and capacity(). resized elements are either default-initialized or assigned a value provided as the second argument.

vector::reserve()

On the other hand, the vector::reserve() method solely allocates memory without initializing any elements. It only affects the capacity(), leaving the size() unchanged. Reserved memory does not contain any object values.

Choosing the Right Method

The choice between resize() and reserve() depends on the desired outcome:

• vector::resize() is preferred when an array of a specific size with default or custom values is needed.
• vector::reserve() is appropriate when allocating memory in advance to avoid multiple reallocations during insertions.

Specific Scenario

In the given scenario, where the initial size is estimated to be around 700-800 with occasional growth, it's generally advisable not to preallocate manually. Instead, it's more efficient to insert elements as needed and let the vector handle dynamic memory management internally.

However, if a reasonably precise estimate of the total size is available upfront, vector::reserve() can be used with that estimate. And if it turns out to be insufficient, the vector will handle the overflow efficiently.

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