More methods of solving The while Loop assignment.

Question

I have solved the assignment in the following way : -
#include <iostream>
using namespace std;

int main()
{
//change the code
int num = 3;
while(num<=20){
cout<<num<<endl;
num += 3;
}

return 0;

However, I felt it was too simple to be true. Are there any more ways of solving the same problem?

Answer 1

I suppose another method of solving it could be using a conditional statement with a modulous and checking it against every increment, like so:

int num = 3;
while(num <=20) {
if(num % 3 == 0) {
cout<<num<<endl;
}
num++;
}

Answer 2

Using for loop instead of while :

for(int num = 3 ; num<=20; num+=3)
cout<<num<<endl;