hen implementing a sequence of elements that needs to grow and shrink dynamically,
std::vector is a fine choice. It provides the convenience of a standard container class, including automatic memory management, random access to elements, a uniform interface, and compatibility with standard algorithms.
However, for a sequence whose size is fixed, the performance hit that comes with all that convenience isn't always justifiable. In particular, a vector incurs the following overhead:
- Nontrivial initialization and destruction. The constructor and destructor of std::vector are relatively costly. This overhead is particularly noticeable when your program creates a large number of vectors.
- Allocation time. Vectors allocate storage for their elements at runtime.
- Space overhead. A vector object typically occupies 32 bytes.
Built-in arrays carry none of this overhead. They allocate their storage statically and have zero space overhead. So why not just use built-in arrays instead for your fixed-sized sequences? Built-in arrays have their own downside: Their security loopholes make them an insecure choice.
Luckily, the C++ Standard Library offers a container-like template called std::array, which offers a secure, efficient, and convenient alternative to built-in arrays—without the overhead of vectors. This 10-Minute Solution shows how to use this powerful alternative for fixed-sized sequences.
How can I implement fixed-sized sequences without the security loopholes of built-in arrays or the noticeable overhead of vectors?
Use std:array as a secure, efficient, and convenient alternative to built-in arrays and vectors for your fixed-sized sequences.
