#include <stdio.h>

/* Written in class 1/30/09 */
void concat(char result[], char s1[], char s2[]) {
  int i = 0;
  int j = 0;
  while (s1[i] != '\0') {
    result[j] = s1[i];
    i++;
    j++;
  }
  for (i=0; s2[i]; i++, j++)
    result[j] = s2[i];
  result[j] = '\0';
}

int main(void) {
  char string1[] = "This is ";
  char string2[] = "a test.";
  char string3[20];

  concat(string3, string1, string2);

  printf("%s\n", string3);

  return 0;
}