A reverse growing number pattern starts at the largest digit and grows rightward each row — 5, then 54, then 543, until the full countdown $rows..1.
Rule: for i = rows down to 1
print digits rows..i
5
54
543
5432
54321 ← rows = 5Unlike Program 7 (prints $i..1 growing from 1), here every row starts at $rows and stops at the current $i. Program 9 continues with repeated digits (1, 22, 333).
Outer loop: $i from $rows down to 1. Inner loop: echo $j from $rows down to $i. End each row with echo PHP_EOL.
| Method | Idea | Best for |
|---|---|---|
| Fixed rows | Hard-code height; outer down, inner $rows..$i | Labs and demos |
| CLI input | Same loops; read $rows at runtime | Interactive practice |
| Spaced digits | echo $j . " " between numbers | Easier reading |
for i from rows down to 1:
for j from rows down to i:
print j
print newline| Goal | Pattern |
|---|---|
| Set size | $rows = 5; |
| Outer (stop digit) | for ($i = $rows; $i >= 1; $i--) |
| Inner (from rows) | for ($j = $rows; $j >= $i; $j--) echo $j; |
| End the row | echo PHP_EOL; |
| Digits on row i | $rows - $i + 1 |
| API | Effect | Use for |
|---|---|---|
echo $j | Stays on the same line | Each digit in the row |
echo PHP_EOL | Ends the current line | After the inner loop finishes |
Build the full countdown with echo, then break once.
Change the row count and the reverse growing pattern updates instantly.
Trace $rows = 5, row $i = 3 — the inner loop builds 543.
| Step | Loop | Result |
|---|---|---|
| Outer | $i = 3 (counting down from 5) | Stop digit = 3 |
| Inner | $j = 5..3 | 543 |
| Break | echo PHP_EOL | Next row starts |
Earlier rows ($i = 5, 4) printed 5 and 54. Later rows extend further toward 1.
Three complete programs: fixed $rows = 5, CLI input, and spaced digits. Use View Output for sample results.
$rows = 5Hard-coded height — outer loop counts down; inner prints $rows..$i.
<?php
$rows = 5;
for ($i = $rows; $i >= 1; $i--) {
for ($j = $rows; $j >= $i; $j--) {
echo $j;
}
echo PHP_EOL;
}
?>1. Start short. When $i = 5, the inner loop prints only 5.
2. Grow right. Each step lowers $i, so the row gains one more digit (54, 543, …).
3. Row break. echo PHP_EOL after the inner loop starts the next line.
Read $rows from the CLI. Prefer is_numeric (shown below).
<?php
echo "Enter the number of rows: ";
$input = trim(fgets(STDIN));
if (!is_numeric($input) || (int) $input < 1) {
echo "Enter a positive whole number." . PHP_EOL;
exit(1);
}
$rows = (int) $input;
for ($i = $rows; $i >= 1; $i--) {
for ($j = $rows; $j >= $i; $j--) {
echo $j;
}
echo PHP_EOL;
}
?>1. Validate input. is_numeric rejects letters; require a positive whole number.
2. Same loops. Descending outer and $rows..$i inner match Example 1 — only the source of $rows changes.
3. Scale. For $rows = 4, the last line is 4321.
Same logic; print a space after each digit for easier reading.
<?php
$rows = 5;
for ($i = $rows; $i >= 1; $i--) {
for ($j = $rows; $j >= $i; $j--) {
echo $j . " ";
}
echo PHP_EOL;
}
?>1. Same shape. Outer and inner bounds are unchanged.
2. Spacing. echo $j . " " separates digits without changing the sequence.
3. Still one break. echo PHP_EOL after the inner loop ends the row.
Check these before calling the solution done.
$i = 1..$rows and $j = $i..1That prints Program 7 (1, 21, 321). Keep outer $rows..1 and inner $rows..$i.
$i instead of $rowsEach row must begin at $rows. Use for ($j = $rows; $j >= $i; $j--).
echo PHP_EOL inside the inner loopThat prints one digit per line. Call echo PHP_EOL only after the inner loop finishes.
Output is one line: 1.
The outer loop never runs. Validate and prompt again for clearer UX.
$rows > 9echo 10 prints two characters and changes visual width. Labs usually stick to 1–9.
| Program | Time | Extra space |
|---|---|---|
| Fixed / input / spaced (Examples 1–3) | O(n²) | O(1) |
There are n rows, and total digits printed are 1 + 2 + … + n = n(n+1)/2, so work is O(n²).
$rows..1, inner $rows..$i — every row starts at $rows.1 downward; this always opens with $rows.echo PHP_EOL advances after the inner loop.1, 22, 333).One line: start each row at $rows and stop at the current $i.
Outer loop counts $i down from $rows; inner loop prints $j from $rows down to $i — 5, 54, 543, … O(n²) for $n rows.
Continue with rows like 1, 22, 333.
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