char *strtok(str, sep) char *str, *sep; char *strsep(str, sep) char *str, *sep;
Strtok is used to isolate sequential tokens in a null-terminated string, str. These tokens are separated in the string by one or more of the characters in sep. The first time that strtok is called, str should be specified; subsequent calls, wishing to obtain further tokens from the same string, should pass a null pointer instead. The separator string, sep, must be supplied each time, and may change between calls. Strtok returns a pointer to the start of each subsequent token in the string, after replacing the token itself with a NUL character. When no more tokens remain, a null pointer is returned.
Strsep behaves similarly to strtok with the exception that the tokens in the string are separated by single occurrences of separator characters. This routine was added to allow handling blank fields.