Is using strlen() in the loop condition slower than just checking for the null character?

Question

I have read that use of strlen is more expensive than such testing like this:

We have a string x 100 characters long.

I think that<

Answer 1

Yes your second may not work 100% percent of the time but it would be slighty quite. This is because when using strlen() you have to call the method each time. A better way would be like so

int strLength = strlen(x);
for (int i = 0; i < strLength; i++)

Hope this helps.