/* Prime number - Program to print prime numbers from 1 to n or between 1 and n or till n */

/* Assume 2 is a prime number but 0 and 1 are not */

#include  <stdio.h>
#include  <conio.h>

void main()
{
    int  n, p, d, flag ;
    clrscr() ;
    printf("Enter n: ") ;
    scanf("%d", &n) ;
    printf("Prime numbers till %d are as shown: \n", n) ;
    for(p=2 ; p<=n ; p++)
        {
            flag=1 ;     /* Assuming p is prime */
            for(d=2 ; d<=p-1 ; d++)   /* d<=p/2 is also correct */
                if(p%d==0)     /* True if number is not prime */
                    {
                        flag=0 ;
                        break ;    /* Inner Loop terminates if p is not prime  */
                    }
            if(flag==1)
                printf("%d ", p) ;
        }
    getch() ;
}

/*
A Similar Program could be:
Program to read two natural numbers r1 and r2 where r2>r1 and generate all prime numbers between r1 and r2 both inclusive.
*/

/*
Output 1:

Enter n: 13
Prime numbers till 13 are as shown:
2 3 5 7 11 13

Output 2:

Enter n: 14
Prime numbers till 14 are as shown:
2 3 5 7 11 13
*/