In this shot, we will discuss how to make a hollow diamond pattern in C++ with stars.

# Approach

We will use the nested loop to generate this pattern. A **nested loop** means there is an *outer* loop inside which there is another loop called an *inner* loop.

Let’s look at the below image to understand this better.




We will generate a hollow full diamond pattern as shown in the image above. We will use the `for` loop and the `while` loop to generate the upper half and the bottom half of the diamond.

# Code

Let’s look at the code snippet below to understand this better.

#include <iostream>
using namespace std;

int main() {
  int number, i, j, k=0;
  cin>> number;
  // upper half of diamond
  for (i = 1; i <= number; i++)
  {
    for (j = 1; j <= number-i; j++)
    {
      cout << " " ;
    }
    while (k != (2*i-1))
    {
      if (k == 0 || k == 2*i-2)
      cout << "*" ;
      else 
      cout << " " ;
      k++;
    }
    k = 0;
    cout << endl;
  }
  // lower half of diamond
    number--;
    for (i = number; i >= 1; i--)
    {
     for (j = 0; j <= number-i; j++)
     {
       cout << " " ;
     }
     k=0;
     while (k != (2*i-1))
     {
       if (k == 0 || k == 2*i-2)
       cout << "*";
       else
       cout << " ";
       k++;
     }
     cout << endl;
    }
  return 0;
}

>Please enter a number above to generate output.

# Explanation

* *In line 5,* we initialize the `number`, `i`, `j`, and `k` variables.

* *In line 6,* we take the input as `number`.

* *From lines 8 to 24,* we initialize a `for` loop and a `while` loop where we have given conditions so as to print `*` and `( )` to generate the upper half of the diamond.

* *From lines 27 to 43,* we initialize another `for` loop and `while` loop where we have given conditions so as to print `*` and `( )` to generate the bottom half of the diamond. We use the *decrement* operator so that `*` gets printed in decreasing order.

In this way, we have learned to generate a hollow full diamond pattern with stars in C++. 

> We can also use numbers, alphabets, or any other characters to generate this pattern.

How to generate a hollow diamond pattern with stars in C++

Nested loops create a hollow diamond pattern with stars in C++. Loops manage both halves.