Thread: Execution of statements in a loop condition

I have for loop that increments through all of the elements inside of an array. If I use the code:

Code:

    for(int i = 0;i < strlen(Buffer);i++)

Is the "strlen(Buffer)" executed every loop? And if so, would it be less overhead if I used a variable to store it?

Code:

    int Length = strlen(Buffer);
    for(int i = 0;i < Length;i++)

Yes and yes. Each strlen() call requires going character by character through the string looking for a '\0'. It's like having a mini for loop in your for loop condition.

It's better to assign it to a local variable before you start the loop for two reasons.

1) it's not executed each time (as anduril pointed out) <--performance issue
2) you can set a breakpoint and see the value before the loop starts <-- troubleshooting issue which, early on, probably trumps the performance issue

Originally Posted by mike65535

2) you can set a breakpoint and see the value before the loop starts <-- troubleshooting issue which, early on, probably trumps the performance issue

Most debuggers will let you print the value of function calls when you're sitting at a breakpoint. In GDB, you would do

Code:

(gdb) p strlen(Buffer)
$1 = 4

Great, thanks for the help