display all the Prime numbers which are less than certain number - c++

Question

I've been learning C++ for few weeks, however, I got stuck, I have a function isPrime(), works great to show if the number is prime or no, I need to display all the Prime numbers which are less than 200. But it's not working see line marked with comment
#include <iostream>
using namespace std;
// Function Prototypes
bool isPrime(int);
int main()
{
int Num;
cout << "This program let you know if the number entered is a "
<< "prime number.\nEnter a number: ";
cin >> Num;
cout << "The number " << Num;
if (isPrime(Num))
{
cout << " is a Prime number." << endl;
}
else
cout << " is not a Prime number." << endl;
return 0;
}
//isPrime
bool isPrime(int Num)
{
if (Num > 1)
{
for (int i = 2; i <= Num; ++i)
{
if (Num % i == 0)
{
if(Num == i)
return true;
else if
for(int n = 2; n < 200; n++) { // HERE
// isPrime will be true for prime numbers
isPrime = isPrimeNumber(n);
if(isPrime == true)
cout<<n<<" ";
}
return 0;
else
return false;
}
}
}
return false;
}

Answer 1

You added the loop in the wrong place. That function is only for checking a particular number. Either you would need to make another function to print all the prime numbers which are less than 200 or you can directly add the loop in the main() function, like i did.
#include <iostream>
using namespace std;
// Function Prototypes
bool isPrime(int);
int main()
{
int Num;
cout << "This program let you know if the number entered is a "
<< "prime number.\nEnter a number: ";
cin >> Num;
cout << "The number " << Num;
// Check numbers here
for(int n = 2; n < 200; n++) {
if (isPrime(n)){
cout << n << " is a Prime number." << endl;
}
}
return 0;
}
//isPrime - This is your original isPrime Code
bool isPrime(int Num)
{
if (Num > 1)
{
for (int i = 2; i <= Num; ++i)
{
if (Num % i == 0)
{
if(Num == i)
return true;
else
return false;
}
}
}
return false;
}