Printing first 100 prime numbers to a file - c++

Question

I have to write out a list of prime numbers from 1-100, using a function we have previously wrote, to a file. The commented out part isn't anything related; it's just the previous code we used for the function. I don't know exactly what's going on because the file isn't even being created, and the part inside the for loop is executing with just 2's, 100 times.
#include <iostream>
#include <fstream>
using namespace std;
bool isPrime(int);
int main () {
ofstream outputFile;
int p = 2;
cout << "I will be giving you the first 100 prime numbers " << endl;
cout << "And giving you a file containing those numbers." << endl;
outputFile.open("PrimeNumbers100.txt");
for (int i = 2; i <= 100; i++)
{
isPrime(p);
cout << p << endl;
outputFile << p << endl;
}
outputFile.close();
cout << "You should now have the file." << endl;
/* int n;
int counter = 0;
int p = 2;
cout << "Welcome to prime counter. " << endl;
cout << "Which prime number would you like? ";
cin >> n;
while (counter < n) {
if (isPrime(p)) {
counter++;
}
p++;
}
p = p - 1;
cout << "Prime number " << n << " is " << p << "." << endl;
*/
return 0;
}
bool isPrime(int p) {
bool result = true;
if (p < 2) {
result = false;
}
else {
int stop = (int) (sqrt(p + .5));
for (int d = 2; d <= stop; d++) {
if (p % d == 0) {
result = false;
break;
}
}
}
return result;
}
Could someone please explain what I'm doing wrong here, and why it isn't even creating the file?

Answer 1

You initialize p at the top with 2. You should be calling isPrime with i instead.

Answer 2

You're getting 2s because you're printing out and storing p, but the loop is going over i.

Answer 3

Here is the updated code. Upon research I did find where it was saving the files, and there are instances of it just not working at all. However, This code runs and does give me everything I need it to.. Thank you for the tips, and I appreciate the very.... constructive feedback.
#include <iostream>
#include <fstream>
using namespace std;
bool isPrime(int);
int main () {
ofstream outputFile;
cout << "I will be giving you the first 100 prime numbers " << endl;
cout << "And giving you a file containing those numbers." << endl;
outputFile.open("PrimeNumbers100.txt");
for (int i = 2; i <= 100; i++)
{
if (isPrime(i)) {
outputFile << i << endl;
}
}
outputFile.close();
cout << "You should now have the file." << endl;
return 0;
}
bool isPrime(int p) {
bool result = true;
if (p < 2) {
result = false;
}
else {
int stop = (int) (sqrt(p + .5));
for (int d = 2; d <= stop; d++) {
if (p % d == 0) {
result = false;
break;
}
}
}
return result;
}