Passing arguments to functions with const parameters: is it faster?

Question

Consider, for example:

int sum(int a, int b)
{
    return a + b;
}

vs.

int sum(const int a, const int b)
{
    return a + b;
}
         


        

Answer 1

No. both of them should be same speed. for your reason, assume it passes the original values in to sum function, how about some code out of the sum function modify the original value, for example, another thread.

In general, the const has no impact the performance at arguments. it do impact the performance if the const is a local/global variable because some calculation can be moved to compiling time as if it is a const.