Are while loops more efficient than for loops

Question

I was told that a while loop was more efficient than a for loop. (c/c++) This seemed reasonable but I wanted to find a way to prove or disprove it.

I have tried three tests using analogous snippets of code. Each containing Nothing but a for or while loop with the same output:

1. Compile time - roughly the same
2. Run time - Same
3. Compiled to intel assembly code and compared - Same number of lines and virtually the same code

Should I have tried anything else, or can anyone confirm one way or the other?

Answer 1

All loops follow the same template:

{
// Initialize
LOOP: 
    if(!(/* Condition */) ) {
        goto END
    }

    // Loop body

    // Loop increment/decrement
    goto LOOP
}
END:

Therefor the two loops are the same:

// A
for(int i=0; i<10; i++) {
    // Do stuff
}

// B
int i=0;
while(i < 10) {
    // Do stuff
    i++;
}

// Or even
int i=0;
while(true) {
    if(!(i < 10) ) {
        break;
    }

    // Do stuff
    i++;
}

Both are converted to something similar to:

{
int i=0;
LOOP: 
    if(!(i < 10) ) {
        goto END
    }

    // Do stuff

    i++;
    goto LOOP
}
END:

Unused/unreachable code will be removed from the final executable/library.

Do-while loops skip the first conditional check and are left as an exercise for the reader. :)