Thread: User to figure out a random number generated by the system.

My code compiles and runs but some parts are not giving the required output. I cannot seem to figure it out. Included are the code and the desired output.

Code:

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#defineMAX_QUERIES12
#defineN_DIGITS4

int isvalid(int n)
{
  if (n <= 0) {
    return 0;
  } else
    return 1;
}

int choose_n(void)
{
  srand(time(0));
  int i;
  int arr[N_DIGITS];
  int num;
  for (i = 0; i < N_DIGITS; i++) {
    num = (rand() % (9 - 1 + 1)) + 1;
    if (isvalid(num)) {
      arr = num;
    }
  }
  int n = arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
  return n;
}

int matches(int n, int m)
{
  int match;
  int n1 = n / 1000;
  int n2 = n / 100 % 10;
  int n3 = n % 100 / 10;
  int n4 = n % 10;
  int m1 = m / 1000;
  int m2 = m / 100 % 10;
  int m3 = m % 100 / 10;
  int m4 = m % 10;
  if (n1 == m1) {
    match++;
  }
  if (n2 == m2) {
    match++;
  }
  if (n3 == m3) {
    match++;
  }
  if (n4 == m4) {
    match++;
  }

  return match;
}

int hits(int n, int m)
{
  int narrayvalue[N_DIGITS] = { 0, 0, 0, 0 };
  int marrayvalue[N_DIGITS] = { 0, 0, 0, 0 };
  narrayvalue[0] = n / 1000;
  narrayvalue[1] = n / 100 % 10;
  narrayvalue[2] = n % 100 / 10;
  narrayvalue[3] = n % 10;
  marrayvalue[0] = m / 1000;
  marrayvalue[1] = m / 100 % 10;
  marrayvalue[2] = m % 100 / 10;
  marrayvalue[3] = m % 10;
  int i;
  int j;
  int hit = 0;
  for (i = 0; i < N_DIGITS; i++) {
    for (j = 0; j < N_DIGITS; j++) {
      if (marrayvalue[j] == narrayvalue) {
        if (i == j) {
        } else {
          hit++;
        }
      }
    }
  }

  return hit;
}

int main(void)
{
  int i;
  int m;
  int n;
  int match;
  int hit;
  printf("***Welcome to the MATCH and HIT game***\n");
  printf("The computer has selected a 4-digit number.\n");
  printf("Try to deduce it in 12 round of queries.\n");
  n = choose_n();
  for (i = 1; i <= MAX_QUERIES; i++) {
    printf("round #%d\n", i);
  loop:printf("Please enter your query (4 digit) :");
    scanf("%d", &m);
    if (isvalid(m)) {
      match = matches(n, m);
      hit = hits(n, m);
      printf("-> %d matches and %d hits\n", match, hit);
      if (match == N_DIGITS) {
        printf("**********************************\n");
        printf("CONGRATULATIONS! You won the game!\n");
        printf("**********************************\n");
        exit(0);
      }
    } else {
      printf("Invalid query. Please try again!\n");
      goto loop;
    }
    match = 0;
    hit = 0;
  }
  printf("*********************************\n");
  printf("Sorry, out of queries. Game over!\n");
  printf("*********************************\n");
  return 0;
}