Alphabet Pattern E to ABCDE in PHP

Beginner
⏱️ 6 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
Fixed right edge
Alphabet pattern output E, DE, CDE, BCDE, ABCDE in PHP programming

What You'll Learn

This PHP program prints a triangle where each row starts one step earlier in the alphabet, but still ends at the same letter (E for 5 rows).

For rows = 5, the output is E, DE, CDE, BCDE, ABCDE.

⭐ Pattern Output

When you run the program with rows = 5:

Output
E
DE
CDE
BCDE
ABCDE
1

Complete PHP Program

Fixed rows = 5 version:

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

$end = $rows - 1; // 4 -> 'E'

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

🧠 How It Works

1

Build an alphabet array

$alpha = range('A', 'Z'); makes it easy to print letters by index.

Setup
2

Fix the ending letter

$end = $rows - 1 is the index of the right-edge letter (E for 5 rows). Every row will end at $alpha[$end].

Right edge
3

Start earlier each row, print forward

Row $i starts at index $end - $i and prints forward up to $end. So the row length is $i + 1.

Inner loop
=

Reverse start, forward run

Total printed letters are 1+2+…+n = n(n+1)/2, so runtime is O(n²).

2

Variation — User Input (CLI) Version

Read rows from standard input (works when you run the file from terminal using php):

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');
$end = $rows - 1;

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

💡 Tips for Enhancement

Try These

  • Compare with Program 2 (reverse letters within the row)
  • Switch to lowercase using range('a', 'z')
  • Add spaces between letters (e.g., echo $alpha[$j] . " ";)
  • Right-align the pattern using leading spaces
  • Use a different ending letter by setting $end manually

Avoid

  • Allowing $rows > 26 without handling wrap-around
  • Using <br> in CLI examples (use PHP_EOL)
  • Off-by-one errors in the start index ($end - $i)
  • Mixing HTML output with CLI output without intent

Key Takeaways

1

Row i prints letters from index end - i to end.

2

The pattern grows by one character per row, like other right-angled triangles.

3

Each row ends at the same letter, so the right edge stays straight.

4

Total printed letters are \(n(n+1)/2\), so runtime is O(n²).

❓ Frequently Asked Questions

In Program 2, each row starts at the same letter and counts backward within the row (E, ED, EDC, ...). In this program, the row starts earlier each time but prints forward to the same ending letter (E, DE, CDE, ...).
Yes. Set $end = 25 and keep $rows small enough so $end - ($rows - 1) stays within A..Z.
It’s O(n²) for n rows, because the program prints 1+2+…+n letters in total.

Next: PHP Alphabet Pattern 4

Continue to Program 4 for the next alphabet pattern in PHP.

Program 4 →
Did you know?

The last letter on row i is always the fixed end letter because the loop always prints up to $end.

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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