Using AVR Libraries

There is a weath of useful functions contained in the AVR-libc libraries that can be found here

Because Arduino already links It links against AVR Libc (the AVR libraries), it is easy to use them. To use a libc library only the header needs to be included in an Arduino sketch. For example to use the strings library functions, one need only include the line

#include <string.h>

in one's sketch.