Thread: help, trying to find prime number

ok, i just started working with c++, and im doing a basic project trying to find all the prime numbers under 100.

here is what i have right now:

Code:

/*variables needed num1, num2, index.
if num1 % num2 = 0 index++, if index = 0 print num1. */
#include <iostream>
using namespace std;

int main ()
{
	int num1, num2;// the 2 numbers we divide to find the remainder
	int remainder, index=0; // remainder determines if the number is prime or not

	for(num1=1; num1 <= 100; num1++) // we take each number under 100
	{
		index = 0;// we reset index back to 0
		for(num2=1; num2< num1; num2++) //and mod it be each number lower than itself
		{
			remainder = num1%num2; // find out the remainder of it
			if(remainder != 0) // and if there is none
			{
				index++; // we increment index once.
			}
		}
		if (index != 0) // if we didnt increment index during that operation
		{	
			cout << num1 << " is a prime number\n"; // it means that num1 is a prime number
		}
	}
	cin.get();
	return 0;
}

issue is, i get 77-100 as prime numbers, nothing before 77 at all, and not only the prime numbers between 77 and 100, but rather 77, 78, 79, 80, etc.

i know i probably made a logic error somewhere along the line.

can someone please look through the code tell me where im wrong. because ive been staring at it for an hour w/ no luck so far.