C Program to check if a number is prime or not in a given interval using function
C Program to check if a number is prime or not in a given interval using function
#include <stdio.h>
// function declaration
int isPrime(int);
void main()
{
int start, end, num;
printf("Enter the number to start: ");
scanf("%d", &start);
printf("Enter the number to end: ");
scanf("%d", &end);
printf("\nPrime numbers between %d to %d are-\n", start, end);
for (num = start; num <= end; num++)
{
if (isPrime(num))
printf("%d\n", num);
}
}
// function definition
int isPrime(int num)
{
// return 1 if number is prime else 0
int i;
for (i = 2; i <= num / 2; i++)
{
if (num % i == 0)
return 0;
}
return 1;
}
Output
Enter the number to start: 1 Enter the number to end: 20 Prime numbers between 1 to 20 are- 1 2 3 5 7 11 13 17 19