Print all prime numbers between an interval

Posted on Apr 8, 2020

C program to print all prime numbers between an interval.

Prime number is a number that is greater than 1 and is divisible only by 1 or itself. In other words, prime numbers can't be divided by other numbers than itself or 1. The first few prime numbers are {2, 3, 5, 7, 11, 13, 17 ...}

Program 

#include<stdio.h>
#include<conio.h>
void main()
{
	int i,j,flag,low,high;

	printf("Enter two values of an interval\t:");
	scanf("%d%d",&low,&high);

	printf("\nPrime numbers between %d and %d are\t:",low,high);

	for(i=low;i<=high;i++)
	{
		flag=0;
		for(j=2;j<=i/2;j++)
		{
			if(i%j==0)
			{
				flag=1;
				break;
			}
		}
		if(flag==0)
		{
			printf("%d\t,",i);
		}
	}

	getch();
}

Output 

Enter two values of an interval :123
345

Prime numbers between 123 and 345 are   :127    ,131    ,137    ,139    ,149    ,151    ,157    ,163    ,167    ,173
,179    ,181    ,191    ,193    ,197    ,199    ,211    ,223    ,227    ,229    ,233    ,239    ,241    ,251    ,257
,263    ,269    ,271    ,277    ,281    ,283    ,293    ,307    ,311    ,313    ,317    ,331    ,337    ,