Growing Suffix Number Pattern in PHP

Beginner
⏱️ 5 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
Nested Loops
Growing suffix number pattern output (5, 45, 345, 2345, 12345) in PHP programming

What You’ll Learn

How to print a growing suffix number pattern in PHP using nested for loops. Each row prints from a decreasing start value up to $n.

This teaches you how to make the inner loop start depend on the outer loop.

⭐ Pattern Output

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

Output
5
45
345
2345
12345
1

Complete PHP Program

Fixed $n = 5 version:

PHP
<?php
$n = 5;

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

🧠 How It Works

1

Choose the size

$n = 5; sets the last digit printed on every row.

Setup
2

Outer loop (start value decreases)

for ($i = $n; $i >= 1; $i--) controls the first digit on each row: 5, then 4, then 3, ...

Row control
3

Inner loop (print $i..$n)

for ($j = $i; $j <= $n; $j++) prints digits from the row start $i up to $n.

Number printing
4

New line

echo PHP_EOL; ends the row and moves to the next line.

Line break
=

Growing suffix pattern

Total printed digits are triangular: 1+2+…+n = n(n+1)/2, so the time complexity is O(n²).

2

Variation — User Input (CLI) Version

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

PHP
<?php
echo "Enter the value of n: ";
$n = (int) trim(fgets(STDIN));

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

💡 Tips for Enhancement

Try These

  • Validate input (reject $n < 1) before printing
  • Add spaces between numbers (for example, echo $j . " ";)
  • Print the “shrinking suffix” by reversing the loop directions
  • Right-align the pattern with leading spaces
  • Use the same idea for alphabet suffix patterns

Avoid

  • Forgetting the newline after each row
  • Using negative or zero values without validating input
  • Mixing up loop directions (outer loop desc, inner loop asc here)
  • Assuming CLI input is always valid (guard fgets() and casting if needed)

Key Takeaways

1

The outer loop chooses the starting digit by counting down from $n to 1.

2

The inner loop prints from $i up to $n for each row.

3

Total printed digits still follow n(n+1)/2, so time complexity is O(n²).

4

This is a classic example of making the inner loop start value depend on the outer loop variable.

❓ Frequently Asked Questions

Because the outer loop starts at $i = $n. The inner loop then runs from $j = $i to $n, so when $i = $n, only one number is printed.
Set $n to the size you want. For example, $n = 7 prints 7, 67, 567, ... up to 1234567.
Yes—use echo $j . " "; instead of echo $j;.
O(n²) for n rows: total prints are 1+2+…+n = n(n+1)/2.

Next: PHP Number Pattern 7

Continue to Program 7 to practice another number pattern using nested loops in PHP.

Program 7 →
Did you know?

This pattern is the “mirror” of an incrementing-start pattern: instead of starting each row at 1 or 2, you start at the row index and extend to the same end value each time.

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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