C++/Advanced Pattern Programs/Program

Pyramid Program

Pyramid Program in C++ (10 Easy Patterns with Code & Output)

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#include <iostream>
using namespace std;

int main() {
    int rows;
    
    cout << "Enter number of rows: ";
    cin >> rows;
    
    // Full Pyramid
    cout << "\nFull Pyramid:" << endl;
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= rows - i; j++) {
            cout << " ";
        }
        for (int j = 1; j <= 2 * i - 1; j++) {
            cout << "*";
        }
        cout << endl;
    }
    
    // Inverted Pyramid
    cout << "\nInverted Pyramid:" << endl;
    for (int i = rows; i >= 1; i--) {
        for (int j = 1; j <= rows - i; j++) {
            cout << " ";
        }
        for (int j = 1; j <= 2 * i - 1; j++) {
            cout << "*";
        }
        cout << endl;
    }
    
    // Hollow Pyramid
    cout << "\nHollow Pyramid:" << endl;
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= rows - i; j++) {
            cout << " ";
        }
        for (int j = 1; j <= 2 * i - 1; j++) {
            if (j == 1 || j == 2 * i - 1 || i == rows) {
                cout << "*";
            } else {
                cout << " ";
            }
        }
        cout << endl;
    }
    
    return 0;
}

Output

Enter number of rows: 5

Full Pyramid:
    *
   ***
  *****
 *******
*********

Inverted Pyramid:
*********
 *******
  *****
   ***
    *

Hollow Pyramid:
    *
   * *
  *   *
 *     *
*********

This program teaches you how to print various pyramid patterns in C++ using nested loops. Pyramid patterns are centered triangular shapes that demonstrate advanced loop control, spacing logic, and pattern formation. They are excellent exercises for understanding nested iterations and are commonly used in programming education and interviews.

1. What This Program Does

The program prints different pyramid patterns based on the number of rows entered by the user. For example, with 5 rows, it creates:

  • Full Pyramid: centered pyramid with increasing stars
  • Inverted Pyramid: upside-down pyramid with decreasing stars

Pyramid patterns require careful control of spaces (for centering) and stars (for the shape) to create symmetric triangular forms.

2. Header File Used

#include <iostream>

This header provides:

  • cout for displaying output
  • cin for taking input from the user

3. Understanding Pyramid Patterns

Key Concepts:

  • Pyramids are centered triangular patterns
  • Require spaces before stars for centering
  • Number of stars follows odd sequence: 1, 3, 5, 7, 9, ...
  • Formula: 2*i - 1 stars in row i

Pattern Types:

  • Full Pyramid: increasing from top (normal pyramid)
  • Inverted Pyramid: decreasing from top (upside-down)
  • Hollow Pyramid: stars only on edges
  • Number Pyramid: numbers instead of stars

4. Declaring Variables

The program declares: int rows;

  • rows stores the number of rows entered by the user.
  • This determines the height of the pyramid.

5. Taking Input From the User

The program asks: cout << "Enter number of rows: "; cin >> rows;

The user enters a number, for example: 5

6. Pattern 1: Full Pyramid

for (int i = 1; i <= rows; i++) { for (int j = 1; j <= rows - i; j++) { cout << " "; } for (int j = 1; j <= 2 * i - 1; j++) { cout << "*"; } cout << endl; }

How it works:

  • Outer loop (i): iterates from 1 to rows (each row)
  • First inner loop: prints (rows - i) spaces for centering
  • Second inner loop: prints (2*i - 1) stars (odd numbers)
  • Creates increasing centered pyramid

Step-by-step (for rows = 5):

Row 1 (i=1):

  • Spaces: 5 - 1 = 4 spaces
  • Stars: 2*1 - 1 = 1 star
  • Output: " *"

Row 2 (i=2):

  • Spaces: 5 - 2 = 3 spaces
  • Stars: 2*2 - 1 = 3 stars
  • Output: " ***"

Row 3 (i=3):

  • Spaces: 5 - 3 = 2 spaces
  • Stars: 2*3 - 1 = 5 stars
  • Output: " ## *"

And so on...

Output (for rows = 5):

*

*

***

## *

7. Pattern 2: Inverted Pyramid

for (int i = rows; i >= 1; i--) { for (int j = 1; j <= rows - i; j++) { cout << " "; } for (int j = 1; j <= 2 * i - 1; j++) { cout << "*"; } cout << endl; }

How it works:

  • Outer loop (i): iterates from rows down to 1 (decreasing)
  • First inner loop: prints (rows - i) spaces (increasing as i decreases)
  • Second inner loop: prints (2*i - 1) stars (decreasing)
  • Creates decreasing centered pyramid

Output (for rows = 5):

## *

***

*

*

8. Understanding the Formulas

Spacing Formula: (rows - i):

  • Row 1: rows - 1 spaces (most spaces)
  • Row rows: rows - rows = 0 spaces (no spaces)
  • Creates centering effect

Star Formula: (2*i - 1):

  • Ensures odd number of stars per row
  • Row 1: 2*1 - 1 = 1 star
  • Row 2: 2*2 - 1 = 3 stars
  • Row 3: 2*3 - 1 = 5 stars
  • Creates pyramid shape

Why Odd Numbers?:

  • Pyramids are symmetric around center
  • Odd numbers allow a center star
  • Even numbers would create asymmetric appearance

9. Other Patterns (Mentioned but not shown in code)

Hollow Pyramid:

  • Print stars only at edges
  • Use conditional: if (j == 1 || j == 2*i-1 || i == rows)
  • Creates outline pyramid

Number Pyramid:

  • Replace stars with numbers
  • Numbers can increase, decrease, or follow sequences
  • Example: 1, 2 3, 4 5 6, ...

Alphabet Pyramid:

  • Use letters instead of stars
  • A, B C, D E F, ...

Floyd's Pyramid:

  • Sequential numbers: 1, 2 3, 4 5 6, 7 8 9 10, ...

Pascal's Pyramid:

  • Mathematical pattern with binomial coefficients
  • More complex pattern

10. When to Use Pyramid Patterns

Educational Purposes:

  • Advanced nested loop practice
  • Understanding spacing and centering
  • Developing pattern recognition

Interview Preparation:

  • Common coding interview problem
  • Tests understanding of loops and formulas
  • Demonstrates logical thinking

Visual Programming:

  • Creating geometric shapes
  • ASCII art generation
  • Pattern-based graphics

11. Important Considerations

Spacing:

  • Single space " " for centering
  • (rows - i) spaces decrease as row increases
  • Proper spacing creates symmetric appearance

Star Count:

  • Formula 2*i - 1 ensures odd numbers
  • Critical for pyramid shape
  • Test with different row counts

Loop Direction:

  • Full pyramid: increasing loop (1 to rows)
  • Inverted pyramid: decreasing loop (rows to 1)
  • Choose based on pattern direction

12. return 0;

This ends the program successfully.

Summary

  • Pyramid patterns use nested loops with spacing and star formulas.
  • Full Pyramid: increasing stars (2*i - 1) with decreasing spaces (rows - i).
  • Inverted Pyramid: decreasing stars with increasing spaces.
  • Formula 2*i - 1 ensures odd number of stars per row for symmetry.
  • Spacing formula (rows - i) centers each row properly.
  • Understanding formulas is essential for pyramid patterns.
  • Variations include hollow, number, alphabet pyramids.
  • Pyramid patterns demonstrate advanced nested loop mastery.

This program is fundamental for beginners learning advanced pattern printing, understanding spacing logic, and preparing for complex pattern problems in C++ programs.

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