Date: 2009may26 Language: C/C++ Q. C/C++: a simple and fast strlen() implementation A. From OpenBSD:

size_t strlen(const char *str) { const char *s; for (s = str; *s; ++s) ; return (s - str); }

glibc's is faster but its crazy complicated http://www.google.com/search?q=glibc+strlen