C Program to Count Number of Prime Numbers in Given Minimum to Maximum Ranges

A Prime Number is a positive integer greater than 1 which is divisible by 1 and itself. In other words, Prime number is a whole number greater than whose factors are 1 and itself. Examples of first few prime numbers are 2, 3, 5, 7, 11, 13..

In this C program, we are going to count such Prime numbers from minimum to maximum value which are given by users.

Program

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

int main()
{
	 int minimum, maximum, flag, count=0, i, j;
	 clrscr();
	 /* Inputs */
	 printf("Enter minimum number: ");
	 scanf("%d", &minimum);
	 printf("Enter maximum number: ");
	 scanf("%d", &maximum);
	 
	 /* Generating and counting prime numbers */
	 for(i=minimum; i<=maximum; i++)
	 {
		  flag = 0;
		  for(j=2; j <= i/2; j++)
		  {
			   if(i%j==0)
			   {
				    flag=1;
				    break;
			   }
		  }
		  if(flag==0 && i>=2)
		  {
		   	printf("%d\t",i);
		   	count++;
		  }
	 }
	 printf("\n Prime Count = %d", count);
	 getch();
	 return(0);
}

Output of the above program :

Run 1:
--------------
Enter minimum number: 100 ↲
Enter maximum number: 200 ↲
101   103   107   109   113   127   131   137   139   149
151   157   163   167   173   179   181   191   193   197
199
Prime Count = 21

Run 2:
--------------
Enter minimum number: -100 ↲
Enter maximum number: 10 ↲
2   3   5   7 
Prime Count = 4

Note: ↲ indicates enter is pressed.