Look at :-
http://www.nongnu.org/avr-libc/user-manual/modules.html
Don`t forget to use #include <????.h>
Look at string.h and stdlib.h
Look at :-
http://www.nongnu.org/avr-libc/user-manual/modules.html
Don`t forget to use #include <????.h>
Look at string.h and stdlib.h