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
}
<         


        

Answer 1

well, I noticed that someone is saying that it is optimized by default by any "clever" modern compiler. By the way look at results without optimization. I tried:
Minimal C code:

#include 
#include 

int main()
{
 char *s="aaaa";

 for (int i=0; i

My compiler: g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Command for generation of assembly code: g++ -S -masm=intel test.cpp

Gotten assembly code at the output:
    ...
    L3:
mov DWORD PTR [esp], 97
call    putchar
add DWORD PTR [esp+40], 1
    .L2:
     THIS LOOP IS HERE
    **mov    ebx, DWORD PTR [esp+40]
mov eax, DWORD PTR [esp+44]
mov DWORD PTR [esp+28], -1
mov edx, eax
mov eax, 0
mov ecx, DWORD PTR [esp+28]
mov edi, edx
repnz scasb**
     AS YOU CAN SEE it's done every time
mov eax, ecx
not eax
sub eax, 1
cmp ebx, eax
setb    al
test    al, al
jne .L3
mov eax, 0
     .....