c++ nested loops code example

Example 1: nested for loops pyramid c++

//C++ program to display hollow star pyramid

#include<iostream>
using namespace std;

int main()
{
   int rows, i, j, space;

   cout << "Enter number of rows: ";
   cin >> rows;

   for(i = 1; i <= rows; i++)
   {
      //for loop to put space in pyramid
      for (space = i; space < rows; space++)
         cout << " ";

      //for loop to print star
      for(j = 1; j <= (2 * rows - 1); j++)
      {
         if(i == rows || j == 1 || j == 2*i - 1)
            cout << "*";
         else
            cout << " ";
      }
      cout << "\n";
   }
   return 0;
}

Example 2: nested loop c++

#include <iostream>
using namespace std;
 
int main () {
   int i, j;
   
   for(i = 2; i<100; i++) {
      for(j = 2; j <= (i/j); j++)
         if(!(i%j)) break; // if factor found, not prime
         if(j > (i/j)) cout << i << " is prime\n";
   }
   
   return 0;
}