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

Yes. The test doesn't know that ss doesn't get changed inside the loop. If you know that it won't change then I would write:

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