Right-Aligned Decreasing Number Pattern in C++

Beginner
⏱️ 6 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
Formatting (setw)
Right-aligned decreasing number pattern output (5, 5 4, 5 4 3, 5 4 3 2, 5 4 3 2 1) in C++ programming

What You’ll Learn

How to print a right-aligned triangle where each row starts from 5 and counts down:

5, then 5 4, then 5 4 3, continuing until 5 4 3 2 1.

We’ll use nested loops, indentation spaces, and setw(2) for clean alignment.

⭐ Pattern Output

For rows = 5, the pattern looks like this:

Output
        5
      5 4
    5 4 3
  5 4 3 2
5 4 3 2 1
1

Complete C++ Program

First we print indentation spaces, then we print numbers from 5 down to the current row limit.

C++
#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int rows = 5;
    int i, j;

    for (i = rows; i >= 1; i--) {
        for (j = 1; j < i; j++) {
            cout << "  ";
        }
        for (j = rows; j >= i; j--) {
            cout << setw(2) << j;
        }
        cout << "\n";
    }

    return 0;
}

🧠 How It Works

1

Set the number of rows

rows = 5 sets both the height and the starting number.

Setup
2

Outer loop counts down

for (i = rows; i >= 1; i--) builds rows from top to bottom.

Row control
3

Indent with spaces

The first inner loop prints 2 * (i - 1) spaces so the numbers align to the right.

Alignment
4

Print 5 down to i

The second inner loop prints numbers rows..i using setw(2) for consistent spacing.

Number printing
=

Right-aligned decreasing triangle

Total printed numbers are n(n+1)/2, so time complexity is O(n²) for n rows.

2

Variation — User Input Version

Let the user choose the starting value (rows) using cin:

C++
#include <iostream>
#include <iomanip>
using namespace std;

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

    cout << "Enter the starting number (rows): ";
    cin >> rows;

    for (i = rows; i >= 1; i--) {
        for (j = 1; j < i; j++) {
            cout << "  ";
        }
        for (j = rows; j >= i; j--) {
            cout << setw(2) << j;
        }
        cout << "\n";
    }

    return 0;
}

💡 Tips for Enhancement

Try These

  • Increase the width in setw() when printing bigger numbers (e.g., setw(3))
  • Print the ascending version by changing the print loop direction
  • Add a separator like a comma to make the output more readable
  • Combine with other rules (like printing only odd numbers) to create new patterns
  • Convert to left-aligned by removing the indentation loop

Avoid

  • Using endl inside loops (it flushes output and slows printing)
  • Hard-coding the pattern size in multiple places
  • Mixing indentation and number printing without a clear structure
  • Forgetting to include <iomanip> when using setw()

Key Takeaways

1

Indentation spaces make the triangle right-aligned.

2

The printed values come from a simple loop: rows down to i.

3

setw(2) keeps spacing uniform for cleaner output.

4

Total printed numbers are n(n+1)/2 so work is O(n²).

❓ Frequently Asked Questions

Because each printed number uses setw(2), so printing " " (two spaces) matches the same width and keeps alignment.
Yes. Store it in rows. The outer loop should run from rows down to 1, and the print loop should run j = rows down to i.
Remove the indentation loop and just print the numbers for each row. You can also print a single space after each number for readability.
O(n²) for n rows: total prints are 1+2+…+n = n(n+1)/2.

Explore More C++ Number Patterns!

Try flipping the loop directions or changing the value rule to generate new right-aligned patterns.

All Number Patterns →
Did you know?

Alignment in console output is usually just a combination of padding (spaces) and fixed-width printing (like setw()).

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

12 people found this page helpful

C++ Number Pattern 35 C++ Number Pattern 37