#include<iostream>

using std::cout;
using std::endl;

#include<iomanip>

using std::setw;

/* write prototype for function prime */

int main()
{
  int count = 0;

  cout << "The prime numbers from 1 to 10000 are:\n";

  for (int loop =2; loop <= 10000; ++loop)

     if ( /* make call to function prime */  ) {
        ++count;
        cout << setw( 6 ) << loop;

     if ( count % 10 == 0)
        cout << '\n';
}

  cout << '\n' << "There were " << count
         << " prime numbers\n";

 return 0;
}
  bool prime (int n)
{
  for ( int i = 2; /*write loop condition */; i++ )

     if( /*write code to test if n is divisible by i */)
        return false;

   return true;
}

# include<iostream.h>
# include<conio.h>

void main()

{
	clrscr();

	int isprime(int);
	int value;

	//input
	cout<<"Enter a number to verify whether it is prime or not "<<endl;
	cout<<"Enter -1 to stop"<<endl;
	cin>>value;

	//output
	while (value!=-1)
		{

		if (isprime(value)==1)
			{
			cout<<"Yes the number is prime"<<endl;
			}
		else
			{
			cout<<"Sorry, not a prime"<<endl;
			}
		getch();
		clrscr();
		cout<<"Enter a number to verify whether it is prime or not "<<endl;
		cin>>value;

		}
}

	//calculation
	int isprime(int valuex)
		{
		int x,j;
		x=1;

		for (j=2 ; j<valuex/2 ; j++)
			{
			if ((valuex%j)==0) x=0;
			}

		if(x!=0) return 1;
		else return 0;
		}

#include <iostream>
using namespace std;

bool isaprime(long);

bool isaprime(long x)
{   long n;
    // is 2 a divisor?
    if ( x%2 == 0)
       return false;
    n = 3;
    while (n*n <=x)
    {   if (x%n == 0)
           return false;
        n += 2;
    }
    return true;
}

int main()
{   long x;
    while (1)
    {   cout <<"Enter a positive integer to check for primality, 0 to exit: ";
        cin >> x;
        if (x == 0)
        {   cout << "Thanks for the fun. Come again.\n";
            return 1;
        }
        if (isaprime(x))
           cout <<x<<" is a prime\n";
        else
           cout <<x<<" is not a prime\n";

   }

}