Will strlen be calculated multiple times if used in a loop condition?

Question

I\'m not sure if the following code can cause redundant calculations, or is it compiler-specific?

for (int i = 0; i < strlen(ss); ++i)
{
    // blabla
}
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Answer 1

The predicate code in it's entirety will be executed on every iteration of the for loop. In order to memoize the result of the strlen(ss) call the compiler would need to know that at least

1. The function strlen was side effect free
2. The memory pointed to by ss doesn't change for the duration of the loop

The compiler doesn't know either of these things and hence can't safely memoize the result of the first call