int main(int argc, char *argv[]) {
   char *x = "hello";                   /* string 1 */
   char *y = "world";                   /* string 2 */
   int n = 3;                           /* number of characters to copy */

   for (int i=0; i<=n; i++) {
      if(i<n) {
         *x++ = *y++;                   /* equivalent of x[i] = y[i] ? */
         printf("%sn", x);             /* just so I can see if something goes wrong */
      } else {
         *x++ = '';                   /* to mark the end of the string */
      }
   }
}

int main(int argc, char *argv[]) {
   char *s;
   char *t;
   int n;                               /* just initilaizing everything I need */

   printf("Enter the string: ");
   scanf("%s", s);                      /* to scan in some phrase */
   printf("%s", s);                     /* to echo it back to me */
}