C++: What is faster - lookup in hashmap or switch statement?

Question

I have a code pattern which translates one integer to another. Just like this:

int t(int value) {
    switch (value) {
        case 1: return const_1;
        ca         


        

Answer 1

A switch statement is going to be quicker than a look up in a hash map.

However, a map is going to result in much more readable code if you ever change the mappings. You can easily do this with a map by reading the results in from a file. In a switch statement you'd have to change the code and recompile.