1 #include <stdio.h> 2 #include <string.h> 3 4 typedef enum { 5 OK, 6 ERROR_NULL_POINTER 7 } status_t; 8 9 status_t string_reverse(char *); 10 void swap_char(char *a, char *b); 11 12 int main (void) 13 { 14 char str[] = "Hello world!"; 15 16 puts(str); 17 string_reverse(str); 18 puts(str); 19 20 return 0; 21 } 22 23 status_t string_reverse(char *str) 24 { 25 if(str == NULL) return ERROR_NULL_POINTER; 26 27 size_t len = strlen(str); 28 for(size_t i = 0; i < (len / 2); i++) 29 swap_char(&str[i], &str[len - 1 - i]); 30 31 return OK; 32 } 33 34 void swap_char(char *a, char *b) 35 { 36 *a = *a + *b; 37 *b = *a - *b; 38 *a = *a - *b; 39 }
