Palindromic Alphabet Pyramid in PHP

Beginner
⏱️ 7 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
Reverse + forward
Alphabet pattern output A, BAB, CBABC, DCBABCD, EDCBABCDE in PHP

What You'll Learn

Each row is built by printing letters in descending order (from the row letter down to B), then ascending order (from A up to the row letter). That forms a palindrome with exactly one A in the middle.

⭐ Pattern Output

For 5 rows:

Output
A
BAB
CBABC
DCBABCD
EDCBABCDE
1

Complete PHP Program (5 Rows)

Fixed version (A..E):

PHP
<?php
$alpha = range('A', 'Z');
$rows = 5; // A..E

for ($i = 0; $i < $rows; $i++) {
    for ($j = $i; $j > 0; $j--) {
        echo $alpha[$j];
    }
    for ($j = 0; $j <= $i; $j++) {
        echo $alpha[$j];
    }
    echo PHP_EOL;
}

🧠 How It Works

1

Outer loop sets the row letter

Row $i peaks at $alpha[$i] (A, B, C, ...).

2

First inner loop prints the left wing

It prints from the peak index down to 1, so it stops before A. That prevents duplicating A at the join.

3

Second inner loop prints A..peak

This loop prints from index 0 up to $i, adding the single center A and completing the palindrome.

4

Print the line break

After building one row, print PHP_EOL to move to the next line. This keeps the output readable in CLI output.

Newline
=

Put it together

The outer loop controls rows, the inner loops control what prints on each row, and PHP_EOL separates the lines.

2

Variation — User Input (CLI) Version

Clamps rows to 26 (A–Z):

PHP
<?php
echo "Enter the number of rows (max 26): ";
$rows = (int) trim(fgets(STDIN));
$rows = max(1, min($rows, 26));

$alpha = range('A', 'Z');

for ($i = 0; $i < $rows; $i++) {
    for ($j = $i; $j > 0; $j--) {
        echo $alpha[$j];
    }
    for ($j = 0; $j <= $i; $j++) {
        echo $alpha[$j];
    }
    echo PHP_EOL;
}

❓ Frequently Asked Questions

It creates an array of uppercase letters so you can print alphabets using simple numeric indexes (0 for A, 1 for B, ...).
PHP_EOL is correct for CLI output and keeps examples consistent for terminal execution. In HTML, you would use <br> instead.
Most pattern programs print O(n) characters per row for n rows, so they are typically O(n2).

Next: PHP Alphabet Pattern 25

Continue to the next program for another alphabet pattern in PHP.

Program 25 →

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)

10 people found this page helpful

PHP Alphabet Pattern 23 PHP Alphabet Pattern 25