Descending Numbers with Diagonal * in PHP

Beginner
⏱️ 6 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
Conditionals
Descending number pattern with diagonal asterisk output in PHP (5432*, 543*1, 54*21, 5*321, *4321)

What You’ll Learn

How to print a descending number pattern in PHP where a diagonal position is replaced with an asterisk:

5432*, 543*1, 54*21, 5*321, *4321.

This pattern is a great way to practice nested loops and a simple if condition.

⭐ Pattern Output

For $n = 5, the pattern looks like this:

Output
5432*
543*1
54*21
5*321
*4321
1

Complete PHP Program

We print $j from $n down to 1, but if $i === $j we print * instead.

PHP
<?php
$n = 5;

for ($i = 1; $i <= $n; $i++) {
    for ($j = $n; $j >= 1; $j--) {
        if ($i === $j) {
            echo "*";
        } else {
            echo $j;
        }
    }
    echo PHP_EOL;
}

🧠 How It Works

1

Set n

$n = 5; defines the range of numbers printed on each row.

Setup
2

Outer loop (rows)

for ($i = 1; $i <= $n; $i++) moves the diagonal position one step each row.

Row control
3

Inner loop (descending numbers)

for ($j = $n; $j >= 1; $j--) prints numbers from 5 down to 1 on each line.

Column control
4

Replace diagonal with *

When $i === $j, we print * instead of the number.

Condition
=

Diagonal star

The matching $i and $j values create a diagonal of asterisks across the output.

2

Variation — User Input (CLI) Version

Let the user choose $n at runtime (run from terminal with php):

PHP
<?php
echo "Enter n (e.g., 5): ";
$n = (int) trim(fgets(STDIN));

if ($n < 1) {
    echo "Please enter a positive number." . PHP_EOL;
    exit(1);
}

for ($i = 1; $i <= $n; $i++) {
    for ($j = $n; $j >= 1; $j--) {
        echo ($i === $j) ? "*" : $j;
    }
    echo PHP_EOL;
}

💡 Tips for Enhancement

Try These

  • Replace * with another symbol to create different diagonal effects
  • Print spaces between numbers for readability when $n is large
  • Create the opposite diagonal by checking $i + $j === $n + 1
  • Turn it into an X pattern by printing stars on both diagonals
  • Use printf padding to align multi-digit numbers

Avoid

  • Mixing loop directions unintentionally (this pattern expects j to count down)
  • Forgetting the newline after each row
  • Skipping input validation for CLI mode
  • Assuming single-digit formatting for large n values

Key Takeaways

1

The inner loop prints descending values from $n to 1.

2

The condition $i === $j identifies the diagonal position.

3

Replacing one position per row creates a clean diagonal effect.

4

The same idea can build X patterns and other matrix-like designs.

❓ Frequently Asked Questions

Use the condition $i + $j === $n + 1 instead of $i === $j.
Yes—print * when $i === $j or $i + $j === $n + 1.
Because the inner loop starts at $j = $n and decrements down to 1.
O(n²) for n rows/columns.

Explore More PHP Number Patterns!

Diagonal conditions like these are the building blocks for many grid and matrix patterns.

All Number Patterns →
Did you know?

In grid problems, diagonals are commonly detected with i === j (main diagonal) and i + j === n + 1 (anti-diagonal).

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)

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