How to print a full pyramid in C++

How to print a full pyramid in C++ :

In this post, we will learn how to print a full pyramid in C++. The program will take the height of the pyramid as input from the user and print it out.

A full pyramid looks as like below:

    *
   * *
  * * *
 * * * *
* * * * *

The height of this pyramid is 5. Our program will print the pyramid of any height.

Algorithm to print a pyramid:

To print a pyramid, we need to find out how it is printed actually. Let’s take a look at the below pyramid:

xxxx*
xxx* *
xx* * *
x* * * *
* * * * *

This is almost similar to the above one. The only difference is that we are using x and the above pyramid uses blank space.

To learn how to print this triangle, let’s write the algo for the second triangle:

For this triangle, height is 5 and if we consider the row is starting from 0,

  • For row 0, we are printing 4 x and 1 *.
  • For row 1, we are printing 3 x and 2 *.
  • For row 2, we are printing 2 x and 3 *.

So, for row n, we are printing height - n - 1 number of x and n + 1 number of *.

For the first triangle, we need to replace x with blank and add one space after each star.

So, the final algorithm will be:

  • Take the height as input from the user
  • Run one loop height number of times.
  • Use two inner loops to print the blank and *. Print blank for height - i - 1 times and * for i + 1 times, where i is the current row as indicated by the loop.
  • Add one blank after each * and don’t add any space between spaces.
  • Add one new line after each row.

C++ program:

Let’s write the above algorithm in C++ :

#include <iostream>
using namespace std;

int main()
{
    int height;
    cout << "Enter the height of the triangle : " << endl;
    cin >> height;

    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < (height - i - 1); j++)
        {
            cout << " ";
        }
        for (int j = 0; j < (i + 1); j++)
        {
            cout << "* ";
        }
        cout << endl;
    }
}

Here,

  • The for loop with i is used to run from i = 0 to i = height - 1.
  • The inner for loops are used to print the blank spaces and *.
  • The first loop prints from j = 0 to j = height - i - 2 a space.
  • The second loop prints * from j = 0 to j = i.

Output:

This program prints the below output:

Enter the height of the triangle : 
10
         * 
        * * 
       * * * 
      * * * * 
     * * * * * 
    * * * * * * 
   * * * * * * * 
  * * * * * * * * 
 * * * * * * * * * 
* * * * * * * * * * 

Enter the height of the triangle : 
5
    * 
   * * 
  * * * 
 * * * * 
* * * * * 

C++ print a pyramid

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