```/*************************************************
How common are primes?

Write a program that reads a number n from the
user and returns the percentage of the first n
integers that are prime (we'll say 1 is *not*
prime).  Write and use a predicate isprime(k)
in your program.  Remember, a number k is prime
if 1 and k are the only numbers that evenly
divide k.
*************************************************/
#include <iostream>
using namespace std;

bool isprime(int);

int main()
{
// Get value n
int n;
cout << "Enter n: ";
cin >> n;

// Count number of primes
int count = 0;
for(int k = 1; k <= n; k++)
if (isprime(k))
count++;

// Compute and print out percentage
double p = count/double(n) * 100.0;
cout << p << "% of the first " << n
<< " integers are prime!" << endl;

return 0;
}

/***********************************
** isprime(k)
***********************************/
bool isprime(int k)
{
// take care of special case k is 1
if (k == 1)
return false;

// search for divisors in [2,k-1]
for(int i = 2; i < k; i++)
if (k % i == 0)
return false;

// no divisors were found, k's prime!
return true;
}

```