Stop using CPP vectors

CPP vectors are great in terms of functionalities but whenever performance is concerned is it reliable? Let's find it out.

Prerequisite:- Arrays, vectors

Introduction to C++ Vectors

C++ vectors are a powerful and convenient container class, offering dynamic resizing and an array-like interface for storing and manipulating data. However, when performance is a critical concern, it's important to consider the overhead that vectors introduce and to limit their use when not necessary.

Memory Management

One major overhead of vectors is the need to maintain a dynamic size, which involves allocating and deallocating memory as the vector grows or shrinks.

When we initialize a vector even with a fixed size, it automatically takes up some extra space, as whenever the space is filled it reinitializes the vector and allocates it to another array with a greater sized array, this operation is costly.

This can lead to performance costs such as cache misses and memory fragmentation, especially when the vector is frequently resized or when working with large datasets.

Accessing an element

Accessing elements in a vector may also be slower than with a built-in array because of the use of pointers and iterators. A built-in array has a continuous block of memory and the elements can be accessed directly with the [] operator, while a vector uses a pointer to the first element, and an iterator is used to access elements.

Additionally, vectors also require additional memory to store their capacity and other bookkeeping information, like the size of the vector, which leads to higher memory usage and may slow down the performance.

It's worth noting that in some cases, the use of vectors may provide a performance boost as it allows for a dynamic size and can reduce the need for manual memory management, but in cases where the size of the container is fixed or performance is a critical concern, it is best to use built-in arrays or other alternative data structures.

Alternatives

One of the best alternatives to vector is the built-in arrays, which are generally faster and take less memory. Other alternatives include std::array, which is a fixed-size container similar to a built-in array, and std::deque, which is a dynamic array that allows for efficient insertion and deletion at both ends.

Conclusion

In summary, while C++ vectors offer a convenient way to store and manipulate data, it's important to consider the performance overhead they introduce and to limit their use when not necessary. Using built-in arrays or alternative data structures such as std::array or std::deque can provide a performance boost in cases where performance is a critical concern.