faster strlen?

Question

Typical strlen() traverse from first character till it finds \\0. This requires you to traverse each and every character. In algorithm sense, its O(N).

Answer 1

The short answer: no.

The longer answer: do you really think that if there were a faster way to check string length for barebones C strings, something as commonly used as the C string library wouldn't have already incorporated it?

Without some kind of additional knowledge about a string, you have to check each character. If you're willing to maintain that additional information, you could create a struct that stores the length as a field in the struct (in addition to the actual character array/pointer for the string), in which case you could then make the length lookup constant time, but would have to update that field each time you modified the string.