A PHP alphabet pattern is a script that prints letters in rows. The outer for loop chooses the last letter of the row. The inner for loop echos each letter, then echo PHP_EOL ends that row.
PHP can increment a one-character string: $letter++ turns 'A' into 'B'. The + operator does not do that. 'A' + $col is addition, so the letter becomes 0. Use chr(ord('A') + $col) when the column is a number.
echo does not end the line.Each echo $letter stays on the current row. Call echo PHP_EOL once, after the inner loop, to start the next row.
Both loops are letters. The inner loop restarts at 'A' and stops when $letter passes $end.
<?php
for ($end = 'A'; $end <= 'E'; $end++) {
for ($letter = 'A'; $letter <= $end; $letter++)
echo $letter; // same row
echo PHP_EOL; // end the row
}Map each part of the console shape to a PHP value or call.
| Piece | PHP | What it does |
|---|---|---|
| Letter | echo $letter | Writes the character and stays on the row |
| Next letter | $letter++ | Advances 'A' to 'B' |
| From a column | chr(ord('A') + $col) | Code of A plus the column, back to a character |
Numeric + | 'A' + $col | Addition: 'A' becomes 0 |
| Concat | 'A' . $col | The string "A1", not B |
| New row | echo PHP_EOL | Ends the row |
| Indent | str_repeat(' ', $n) | $n spaces |
| Prefix | substr($letters, 0, $n) | First $n characters of a string |
Three scripts. Each one changes only the PHP that chooses the letter or the leading spaces.
The outer loop stops at 'E'. The inner loop reprints from 'A' through the current end letter.
<?php
for ($end = 'A'; $end <= 'E'; $end++) {
for ($letter = 'A'; $letter <= $end; $letter++) {
echo $letter;
}
echo PHP_EOL;
}$end++ moves the end letter from A toward E.'A', so every row begins with A.echo $letter stays on the row. echo PHP_EOL starts the next one.ord('A') is the code for A. Add the column, then chr turns that sum back into a letter.
<?php
$rows = 4;
for ($row = 0; $row < $rows; $row++) {
for ($col = 0; $col <= $row; $col++) {
echo chr(ord('A') + $col);
}
echo PHP_EOL;
}echo 'A' + $col prints a number, because + casts 'A' to 0.ord reads the code, the addition stays numeric, and chr returns the letter.PHP_EOL.str_repeatPrint the spaces before the letters. The letter loop is unchanged.
<?php
$rows = 5;
for ($row = 1; $row <= $rows; $row++) {
echo str_repeat(' ', $rows - $row);
for ($letter = 'A'; $letter < chr(ord('A') + $row); $letter++) {
echo $letter;
}
echo PHP_EOL;
}str_repeat(' ', $rows - $row) writes 4 spaces on row 1 and none on row 5.chr(ord('A') + $row) is the first letter that should not print.echo PHP_EOL still closes the row after the spaces and the letters.Each card is a full PHP script: nested for loops, a letter for the cell, and echo. Open one for the walkthrough.
A full PHP walkthrough of the right-angled letter triangle, from $letter++ through echo PHP_EOL.
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