Beginning C++ program question

[CJ_NOE]

I need to wright a program to compute the number of prime numbers in the first 50 "chiliads”. Yes sounds confusing but it just has to out put this basically.

Start End Number of Primes
1 1000 168
1001 2000 135
2001 3000 127
3001 4000 120
4001 5000 119
5001 6000 114
6001 7000 117
7001 8000 107
8001 9000 110
9001 10000 112
…
…
…
49001 50000 98

So far I have only been working on a function proto. to find prime numbers.

#include <iostream>

using namespace std;

int prime_num(int);

int main()
{
    cout << " Enter a number and I will generate the prime numbers up to that number: ";
    int num = 0;
    cin >> num;
    prime_num(num);
        //cout << num << endl; not used
    
}
 
int prime_num( int num)
{
        bool isPrime=true;
        
        // for (initial statement; loop condition ; update statement)
        
        for ( int i = 2; i <= num; i++)
        {
                for ( int j = 2; j <= num; j++)
                {
                        if ( i != j && i % j == 0 )
                        {
                          isPrime=false;
                          break;
                        }
                }
                if (isPrime)
                {
                  cout << i << endl;
                }
                isPrime=true;
        }
}

How do I get this to count the number of primes rather then display them?

And once it has counted them display them like the above example?

THANK YOU!

[iamthwee]

>How do I get this to count the number of primes rather then display them?

set up a counter...
you initialise the counter before the main body of the for or while loop.

[hollystyles]

Prime numbers comes up quite a lot, have you searched the forum ?

http://www.daniweb.com/techtalkforums/showthread.php?t=43892&page=2&highlight=prime+number