ex_4-13.c

   1 #include <string.h>
   2 #include <stdio.h>
   3
   4 /* print contents of array */
   5 void print_array(char s[])
   6 {
   7         int i;
   8         for(i = 0; i < strlen(s); i++)
   9                 printf("%c", s[i]);
  10         printf("\n");
  11 }
  12
  13 /* reverse contents of array in place */
  14 void rev_array(char s[])
  15 {
  16         int c, i, j;
  17         for(i = 0, j = strlen(s)-1; i < j; i++, j--)
  18         {
  19                 c = s[i];
  20                 s[i] = s[j];
  21                 s[j] = c;
  22         }
  23 }
  24
  25 /* helper function - performs the recursion */
  26 int rec_rev(char s[], int i, int j)
  27 {
  28         char c;
  29
  30         c = s[i];
  31         s[i] = s[j];
  32         s[j] = c;
  33
  34         if(i < j)
  35         {
  36                 i++;
  37                 j--;
  38                 rec_rev(s, i, j);
  39         }
  40
  41         return 1;
  42 }
  43
  44 /* reverse contents of array recursively in place */
  45 void rev_array_rec(char s[])
  46 {
  47         int i = 0;
  48         int j = strlen(s)-1;
  49         rec_rev(s, i, j);
  50 }
  51
  52
  53 int main()
  54 {
  55         char s[10] = { "Reverse Me" };
  56
  57         print_array(s);
  58         rev_array_rec(s);
  59         print_array(s);
  60         return 1;
  61 }