Using arrays or std::vectors in C++, what's the performance gap?

Question

In our C++ course they suggest not to use C++ arrays on new projects anymore. As far as I know Stroustroup himself suggests not to use arrays. But are there significant perf

Answer 1

STL is a heavily optimized library. In fact, it's even suggested to use STL in games where high performance might be needed. Arrays are too error prone to be used in day to day tasks. Today's compilers are also very smart and can really produce excellent code with STL. If you know what you are doing, STL can usually provide the necessary performance. For example by initializing vectors to required size (if you know from start), you can basically achieve the array performance. However, there might be cases where you still need arrays. When interfacing with low level code (i.e. assembly) or old libraries that require arrays, you might not be able to use vectors.