C and pointer (pointers on C) -- Chapter 6: pointer (ii) exercises

It is difficult for the author to answer the first three questions!

Please see http://download.csdn.net/download/wangpegasus/5701765

1,

 
Char * find_char (char const * Source, char const * chars) {char * PTR; If (source! = NULL & chars! = NULL) {for (; * Source! = '\ 0'; source ++) {for (PTR = (char *) chars; * PTR! = '\ 0'; PTR ++) {If (* PTR = * Source) {return (char *) Source ;}}} return NULL ;}
 

2,

Char * match (char * string, char * sub) {While (* sub! = '\ 0') {string ++; sub ++; If (* string! = * Sub) {return NULL;} return string;} int del_substr (char * STR, char const * substr) {char * PTR; PTR = NULL; if (STR = NULL & substr = NULL) {return 0 ;}for (; * Str! = '\ 0'; STR ++) {PTR = match (STR, (char *) substr); If (PTR! = NULL) {break;} while (* STR ++ = * PTR ++) {;} return 1 ;}
 

3,

 
Void reverse_string (char * string) {char temp; char * last; last = string; If (string! = NULL) {While (* last! = '\ 0') {last ++;} Last --; while (string> last) {temp = * last; * Last = * string; * string = temp; string --; last ++ ;}}}