C program to display all prime numbers between Two interval entered by user

 #include <stdio.h>

int main()

{

  int n1, n2, i, j, flag;

  printf("Enter two numbers(intevals): ");

  scanf("%d %d", &n1, &n2);

  printf("Prime numbers between %d and %d are: ", n1, n2);

  for(i=n1+1; i<n2; ++i)

  {

      flag=0;

      for(j=2; j<=i/2; ++j)

      {

        if(i%j==0)

        {

          flag=1;

          break;

        }

      }

      if(flag==0)

        printf("%d ",i);

  }

  return 0;

}



Output

Enter two numbers(intervals): 20
50
Prime numbers between 20 and 50 are: 23 29 31 37 41 43 47