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Printing prime numbers
Sep 11, 2015 at 6:33pm
What does count and num does?Why is num inititalized to 3?why is square root of 3 in for loop?
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int n, status = 1, num = 3, count, c;
cout << "Enter the number of prime numbers to print\n";
cin >> n;
if (n >= 1)
{
cout << "First " << n << " prime numbers are :-" << endl;
cout << 2 << endl;
}
for (count = 2; count <= n; )
{
for (c = 2; c <= (int)sqrt(num); c++)
{
if (num%c == 0)
{
status = 0;
break;
}
}
if (status != 0)
{
cout << num << endl;
count++;
}
status = 1;
num++;
}
system("pause");
}
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int n, status = 1, num = 3, count, c;
cout << "Enter the number of prime numbers to print\n";
cin >> n;
if (n >= 1)
{
cout << "First " << n << " prime numbers are :-" << endl;
cout << 2 << endl;
}
for (count = 2; count <= n; )
{
for (c = 2; c <= (int)sqrt(num); c++)
{
if (num%c == 0)
{
status = 0;
break;
}
}
if (status != 0)
{
cout << num << endl;
count++;
}
status = 1;
num++;
}
system("pause");
}
Sep 11, 2015 at 6:40pm| What does count and num do? |
count is the number of primes found.
num is the number that is being tested to determine if it is prime.
| Why is num initialized to 3 |
That is the first prime > 2.
| why is square root of 3 in for loop? |
A factor of a prime number can't be greater than its square root, so no point in checking values greater than the square root.
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