Eventually the topic of recursion comes up in programming.   It means "in the body of function xyz(), there is a call to function xyz()".  More simply, the function calls itself.  There is one cardinal rule.

 

handpntright Inside the recursive function, there MUST BE some sort of "exit condition"

 

(right-click to download)

/* pgm29 source */

#include <stdio.h>
#include <string.h>

void reverse(char *, char *);

int main(void) {
     char *srcstr = "Joe loves Tina's smile!";
     char *startp;
     char *endp;
     int slen;

     startp = srcstr;

     slen = strlen(srcstr);
     endp = startp + (slen - 1); // output from program helps see this

     printf("\nCharacter string (length %d):\n\n%s\n\n", slen, srcstr);

     printf("\"startp\" contains memory address %p, points to '%c'\n", (void *) startp, *startp);
     printf("\"endp\" contains memory address %p, points to '%c'\n\n", (void *) endp, *endp);

     printf("Two examples of \"pointer math\":\n");
     printf("Character found at \"startp + 3\": %c\n", *(startp + 3));
     printf("Character found at \"startp + 10\": %c\n\n", *(startp + 10));

     printf("Reversed string:\n\n");
     reverse(startp, endp);
     printf("%c\n", *startp); // after exiting the recursion, we need to print one more character

     printf("\n\n");
     return(0);
     }

/* as long as "backwards-moving pointer 'endp' */
/* does not equal 'startp', the recursion keeps   */
/* going, where the function CALLS ITSELF     */
void reverse(char *startp, char *endp) {
     if (startp != endp) {
          printf("%c", *endp);
          endp--;
          reverse(startp, endp);
          }
     }

 

 

recursive_rooms