PHP Reverse Alphabet Pyramid Pattern (Slice from E)

Beginner
7 min read
Updated: Sep 2026
3 programs
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Right-aligned reverse alphabet pyramid output in PHP programming
Definition

What Is This Pattern?

A right-aligned reverse alphabet pyramid prints a growing reverse slice each row — from a single top letter down to a full E D C B A base — with padding so the block stays right-aligned.

Remember
Rule: for i from top down to 'A',
      print pads for A..(i-1), then letters top..i (width 2)

         E
       E D
     E D C
   E D C B
 E D C B A     ← top = 'E' (monospace)

Companion to Program 22: same fixed-width grid (two spaces for pads + width-2 letter cells), but each row prints a reverse slice top..i instead of a running sequential counter.

Approach

How to Solve It

Two ways to emit the same shape — start with char loops, then optionally rewrite with int row indexes.

MethodIdeaBest for
Char loopsOuter $i; pad A..(i-1); letters top..iLearning, interviews, exams
Int row indexPad $n - $row; print $row letters from $top downWhen you think in row numbers

Pseudocode

Pseudocode
for $i from $top down to 'A':
    for $j from 'A' to ($i - 1):
        echo "  "
    for $j from $top down to $i:
        echo $j in width-2 field
    echo PHP_EOL

Cheat sheet

GoalPattern
Countdown rowsfor ($i = $top; $i >= 'A'; $i--)
Pad cellsfor ($j = 'A'; $j < $i; $j++) echo " ";
Reverse slicefor ($j = $top; $j >= $i; $j--) echo " " . $j;
End the rowecho PHP_EOL;
Row count$n = ord($top) - ord('A') + 1
Pad count for $iord($i) - ord('A') (4 when $i is E)
Sequential twinProgram 22 ($k++)

Printing Letters vs Starting a New Line

APIEffectUse for
echoStays on the same lineEach pad cell and each letter
echo PHP_EOLEnds the current lineAfter both inner loops

Print cells without a newline, then end the row once.

Try it

Live Preview

Change the top letter and the right-aligned reverse pyramid updates instantly.

One letter from A to F. Tap a chip or type a letter — the preview redraws as you go.

Live result Top E · 5 rows · 15 letters
         E
       E D
     E D C
   E D C B
 E D C B A
Trace

Worked Walkthrough — Top = E

Trace each row’s pads, reverse slice, and printed line (each cell is width 2).

$iPad cellsLettersPrinted row
E4EE
D3E DE D
C2E D CE D C
B1E D C BE D C B
A0E D C B AE D C B A

Row count = ord($top) - ord('A') + 1 (5 for E). Letter total: 1 + 2 + 3 + 4 + 5 = 15 = 5×6/2.

Code

PHP Programs

Three complete programs: fixed top letter, CLI input, and an int-index rewrite. Use View Output to reveal sample results.

Example 1 — Fixed A–E

Hard-coded top E — pad first, then print letters from E down to the current row letter.

PHP
<?php
for ($i = 'E'; $i >= 'A'; $i--) {
    for ($j = 'A'; $j < $i; $j++)
        echo "  ";

    for ($j = 'E'; $j >= $i; $j--)
        echo " " . $j;

    echo PHP_EOL;
}
?>

How It Works

1. Outer loop descends. $i runs from 'E' down to 'A' — one row per letter.

2. Pad first. Print " " for each $j from 'A' to $i - 1 so the letters stay right-aligned.

3. Reverse slice. Print $j from 'E' down to $i as " " . $j (width-2 cells).

4. Break the line. echo PHP_EOL; after both inner loops starts the next row.

When $i = 'C', pads run for A and B, then letters print E D C.

Example 2 — Top Letter Input

Read the top letter at runtime. Prefer validating a single A–Z character in real apps.

PHP
<?php
echo "Enter the top letter (like E): ";
$top = strtoupper(trim(fgets(STDIN)))[0];

for ($i = $top; $i >= 'A'; $i--) {
    for ($j = 'A'; $j < $i; $j++)
        echo "  ";

    for ($j = $top; $j >= $i; $j--)
        echo " " . $j;

    echo PHP_EOL;
}
?>

How It Works

1. Prompt and read. Ask for a top letter, then take the first character (uppercased).

2. Same pad/letter core. Both the outer start and the letter-loop start use $top.

3. Safer input tip. Taking [0] fails on empty tokens. Prefer:

Safer input
$raw = strtoupper(trim(fgets(STDIN)));
if (strlen($raw) !== 1 || $raw < 'A' || $raw > 'Z') {
    echo "Enter one letter from A to Z." . PHP_EOL;
    exit;
}
$top = $raw;

Example 3 — Int Row Index

Same shape with integer indexes: pad $n - $row cells, then print $row letters from the top down.

PHP
<?php
$top = 'E';
$n = ord($top) - ord('A') + 1;

for ($row = 1; $row <= $n; $row++) {
    for ($s = 0; $s < $n - $row; $s++)
        echo "  ";

    for ($k = 0; $k < $row; $k++)
        echo " " . chr(ord($top) - $k);

    echo PHP_EOL;
}
?>

How It Works

1. Derive height. $n = ord($top) - ord('A') + 1 is 5 when $top is 'E'.

2. Pad by row number. Row 1 pads $n - 1 cells; the last row pads 0.

3. Letters from the top. Letter $k is chr(ord($top) - $k) — row 1 prints E; row 5 prints E..A.

Edge Cases & Pitfalls

Check these before calling the solution done.

Single space

Broken alignment

Pads must be " " (two spaces) to match width-2 letter cells. One space skews the pyramid in monospace output.

PHP_EOL inside

Broken outline

If echo PHP_EOL is inside either inner loop, each cell lands on its own line. Use echo for pads and letters; end the row only after both loops.

$j <= $i

Extra pad cell

The pad loop must stop at $j < $i, not $j <= $i, or you insert one too many empty cells.

$top = A

Single letter

Output is just a width-2 A cell. Pad loop never runs. A good sanity check.

$top < A

Empty output

Outer loop never runs if $top < 'A'. Validate A–Z before looping.

Bad input

Validate one letter

Empty, multi-character, or lowercase-only handling — trim, uppercase, and require length 1 in A–Z.

Analysis

Time and Space Complexity

ProgramTimeExtra space
Char loops (Examples 1–2)O(n²)O(1)
Int row index (Example 3)O(n²)O(1)

For $n = ord($top) - ord('A') + 1 rows, each row does up to O(n) pad + letter writes. Letter total = 1 + 2 + … + n = n(n + 1)/2.

Remember

Key Takeaways

  • Rule: for $i from $top down to 'A', pad A..(i-1), then print top..i.
  • Fixed width: use " " pads and " " . $letter so every cell is two columns.
  • Break the row: call echo PHP_EOL only after both inner loops.
  • Complexity: O(n²) time; O(1) extra space.

One line: for each row letter $i from top down to A, echo pads for A..(i-1), then letters top..i with width 2, then echo PHP_EOL.

Frequently Asked Questions

The first prints padding so the visible letters are right-aligned. The second prints letters from E (or your top letter) down to the current row letter i.
Each letter is printed as a leading space plus the character. Two spaces keep empty cells the same width so the pyramid aligns in monospace output.
Program 22 uses one running counter k++ across all rows (A..O). Program 23 prints a reverse slice each row using the loop variable j (E..i).
echo stays on the same line for pads and letters. echo PHP_EOL ends the row after both inner loops finish.
Yes. Change the second loop to always begin from your chosen top letter and decrement to the row letter — Example 2 does this with user input.
O(n²) for n rows because each row does O(n) work across the padding + letter loops.
Use trim(fgets(STDIN)), take the first character after strtoupper, require A–Z, and reject empty or multi-character tokens.
For top = E, when i is E you print 4 pad cells (A..D); when i is A you print 0. Pads = (ord($i) − ord('A')).

Did you know?

Outer i runs from E down to A. The first inner loop prints one " " per j with A <= j < i (so the block shifts left each row). The second loop prints letters from E down to i as width-2 cells (" " . $j).

Next: Palindromic Pyramid

Move from reverse slices to mirrored letter rows (A, BAB, CBABC, …).

Program 24 tutorial →

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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PHP Alphabet Pattern 22 — Right-Aligned Sequential PHP Alphabet Pattern 24 — Palindromic Pyramid