I'm writing a program to calculate the number of prime numbers in a sequence. There's a variable called num that is given and then the program must calculate how many prime numbers there are from 2 (the smallest prime number) to num.

It should be something like that:

Enter a number greater than 1: 7 There are 4 prime numbers between 2 and 7.

This is because 2,3,5 and 7 are prime numbers, a total of 4 numbers.

The code below shows the variable num which is equal to 7, the main function calls isPrime (which says if a number is prime or not), then the way I thought about was using a for loop from 2 to num and check if each i is prime or not.

I don't know how to proceed from that. Please, could someone help?

#include <stdio.h>

#include <math.h>

int isPrime(int num) {

int i;

for (i=2; i<=sqrt(num); i++) {

if (num%i == 0) {

return 0;

}

}

return 1;

}

int main(){

int i, num, numofprimes;

num=7;

for (i=2;i<=num;i++){

if (isPrime(i)){

}

printf("%d", numofprimes);

}

return 0;

}

If someone could help I would be glad.