char * strtok(char *, const char *)
strtok parses the string s into tokens. The first call to strtok should have s as its first argument. Subsequent calls should have the first argument set to NULL. If a token ends with a delimiter, this delimiting character is overwritten with a '\0' and a pointer to the next character is saved for the next call to strtok. The delimiter string delim may be different for each call.
The strtok() function returns a pointer to the next token or NULL when no more tokens are found.
strtok() is NOT reentrant. For a reentrant version of this
function see strtok_r().