char *Chop(char *str); 
char *Crypt(char *str);              
char *Ltrim(char *str);
char *Rtrim(char *str);
char *Trim(char *str);
char *Str_Repeat(char *input, int multiplier);
char *Str_Replace (char *search, char *replace, char *subject);
char *Str_Rot13(char *str);
char *Stristr(char *haystack, char *needle);
char *Strrev(char *string);
char *Strtolower (char *str);
char *Strtoupper (char *str);
int Substr_count (char *haystack, char *needle);