Assigning character to a character variable in a nested loop does not work in c

I'm making a code to generate a random rank for a college assignment. And the program looks like this:

#include <conio.h>
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

char rankgen()
{
  char rank;
  int randnum = (rand() % 13) + 1;
  // printf("randnum: %d\n", randnum);

  if (randnum != 1 || randnum != 11 || randnum != 12 || randnum != 13
      || randnum != 10) {
    rank = randnum + '0';
  } else {
    if (randnum == 10)
      rank = 1 + '0';
    else if (randnum == 1)
      rank = 'A';
    else if (randnum == 11)
      rank = 'J';
    else if (randnum == 12)
      rank = 'Q';
    else if (randnum == 13)
      rank = 'K';
  }
  return rank;
}

char rankgen2()
{
  char rank;
  int randnum = (rand() % 13) + 1;
  // printf("randnum: %d\n", randnum);

  if (randnum != 1 || randnum != 11 || randnum != 12 || randnum != 13
      || randnum != 10) {
    rank = randnum + '0';
  }
  if (randnum == 10)
    rank = 1 + '0';
  if (randnum == 1)
    rank = 'A';
  if (randnum == 11)
    rank = 'J';
  if (randnum == 12)
    rank = 'Q';
  if (randnum == 13)
    rank = 'K';
  return rank;
}

int main()
{
  srand(time(NULL));
  for (int i = 0; i < 30; i++) {
    char rank = rankgen();
    char rank2 = rankgen2();
    printf("%c, %c\n", rank, rank2);
  }
  return 0;
}

It seems like I can't assign a char into a char variable when using a nested loop or in an if-else statement. I could temporarily fix that by making it not inside any of the loop or any statement. It would help a lot if you explain why does it happen and how to fix it.

You only need one rankgen function (since they both do exactly the same thing), and it should look something like this:

char rankgen()
{
    char rank;
    int randnum = (rand() % 13) + 1;

    if (randnum == 1)
        rank = 'A';
    else if (randnum == 10)
        rank = 'T';
    else if (randnum == 11)
        rank = 'J';
    else if (randnum == 12)
        rank = 'Q';
    else if (randnum == 13)
        rank = 'K';
    else
        rank = randnum + '0';
    return rank;
}

Note that as @EugeneSh pointed out, the initial if statement is wrong; since no value can be equal to more than one different value, it will always be false. Because of this, most of the time you return a garbage value in rank. Also, I'm not sure what you meant for your == 10 case to do, but I changed it to make the character 'T' (for "Ten").

You could also do this with a switch statement like this:

char rankgen()
{
    char rank;
    int randnum = (rand() % 13) + 1;

    switch (randnum) {
        case 1:
            rank = 'A';
            break;
        case 10:
            rank = 'T';
            break;
        case 11:
            rank = 'J';
            break;
        case 12:
            rank = 'Q';
            break;
        case 13:
            rank = 'K';
            break;
        default:
            rank = randnum + '0';
            break;
    }
    return rank;
}