strtok()
It is C library string function.

Syntax:

include 
char *strtok( char *str1, const char *str2 );

Description:
The strtok() function returns a pointer to the next "token" in str1, where str2 contains the delimiters that determine the token. strtok() returns NULL if no token is found. In order to convert a string to tokens, the first call to strtok() should have str1 point to the string to be tokenized. All calls after this should have str1 be NULL.