21.Write a programme using switch

#include <stdio.h>

int main() {
  int day = 4;
  
  switch (day) {
    case 1:
      printf("Monday");
      break;
    case 2:
      printf("Tuesday");
      break;
    case 3:
      printf("Wednesday");
      break;
    case 4:
      printf("Thursday");
      break;
    case 5:
      printf("Friday");
      break;
    case 6:
      printf("Saturday");
      break;
    case 7:
      printf("Sunday");
      break;
  }
    
  return 0;
}

22.Write a programme using while loop 

#include<stdio.h>
int main() {
  int i = 0;
  
  while (i < 5) {
    printf("%d\n", i);
    i++;
  }
  
  return 0;
}

OUTPUT

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