A remove-last-digit pattern prints a number, then drops its rightmost digit each line — 86523 → 8652 → 865 → 86 → 8 — until nothing remains.
Rule: while num != 0
print num
num = intdiv(num, 10)
86523
8652
865
86
8 ← start = 86523Unlike nested-loop triangles (Programs 1–59), this uses one while loop and integer division. Program 61 builds a number by reversing digits progressively.
Print the current value, then set $num = intdiv($num, 10). Repeat while $num != 0. Prefer intdiv over float division so results stay exact integers.
| Method | Idea | Best for |
|---|---|---|
| Fixed number | while + intdiv($num, 10) | Labs and demos |
| CLI input | Same loop; read $num at runtime | Interactive practice |
| String prefixes | substr($s, 0, $len) shrinking length | Avoiding division |
num = starting value
while num != 0:
print num and newline
num = integer divide num by 10| Goal | Pattern |
|---|---|
| Set start | $num = 86523; |
| Loop | while ($num != 0) { ... } |
| Print line | echo $num . PHP_EOL; |
| Drop last digit | $num = intdiv($num, 10); |
| String alternative | echo substr($s, 0, $len) . PHP_EOL; |
| API | Effect | Use for |
|---|---|---|
echo $num | Stays on the same line | Rare here — usually you want a full line |
echo $num . PHP_EOL | Prints value and ends the line | Each shortened number (this pattern) |
Same idea as C# WriteLine: one number per line. Nested-row patterns use echo for digits and echo PHP_EOL after the row.
Change the starting number and each digit-removal line updates instantly.
Trace $num = 86523 — each step prints, then divides by 10.
| Iteration | After intdiv(..., 10) | |
|---|---|---|
| 1 | 86523 | 8652 |
| 2 | 8652 | 865 |
| 3 | 865 | 86 |
| 4 | 86 | 8 |
| 5 | 8 | 0 → loop ends |
0 is never printed — the while condition fails before that iteration.
Three complete programs: fixed $num = 86523, CLI input, and a substr variant. Use View Output for sample results.
$num = 86523Print the current value, then divide by 10 until the number becomes zero.
<?php
$num = 86523;
while ($num != 0) {
echo $num . PHP_EOL;
$num = intdiv($num, 10);
}
?>1. Print first. Each iteration outputs the current $num before shrinking it.
2. Drop a digit. intdiv($num, 10) removes the last digit (discarding the remainder).
3. Stop at zero. When division yields 0, while ($num != 0) ends — 0 is not printed.
Read the starting number from the CLI. Prefer is_numeric (shown below).
<?php
echo "Enter a number: ";
$input = trim(fgets(STDIN));
if (!is_numeric($input) || (int) $input == 0) {
echo "Enter a non-zero whole number." . PHP_EOL;
exit(1);
}
$num = abs((int) $input);
while ($num != 0) {
echo $num . PHP_EOL;
$num = intdiv($num, 10);
}
?>1. Validate input. is_numeric rejects letters; reject zero so the loop would otherwise print nothing.
2. Use abs. abs((int) $input) keeps lines positive if the user types a negative value.
3. Same while loop. Print and intdiv match Example 1 — only the source of $num changes.
Same output using string prefixes instead of division.
<?php
$num = 86523;
$s = (string) $num;
for ($len = strlen($s); $len >= 1; $len--) {
echo substr($s, 0, $len) . PHP_EOL;
}
?>1. Convert once. Store the digits as a string so length is known up front.
2. Shorten prefixes. substr($s, 0, $len) keeps the leftmost $len characters.
3. Same look. Visual result matches Examples 1–2 without intdiv.
Check these before calling the solution done.
$num / 10 without intdivIn PHP, / can yield floats. Prefer intdiv($num, 10) (or (int) ($num / 10)) for clean integers.
That skips the full starting number. Print first, then intdiv.
The loop never runs — no output. Validate and ask for a non-zero value.
120 → 12 → 1. Trailing zeros disappear in one step like any last digit.
Without abs, lines may show a minus. Example 2 takes the absolute value first.
Output is a single line (e.g. 7), then division yields 0 and the loop stops.
| Program | Time | Extra space |
|---|---|---|
| while + intdiv (Examples 1–2) | O(d) | O(1) |
| String substr (Example 3) | O(d²) worst case for substr copies | O(d) for the string |
For d digits, the while-loop version runs exactly d iterations — linear in the digit count, not in the numeric magnitude alone.
intdiv($num, 10), until $num is 0.One line: print the number, divide by 10, repeat until nothing is left.
Integer division by 10 drops the last digit each step — 86523 becomes 8652, then 865, 86, 8. One while loop, O(d) time for d digits. Prefer intdiv($num, 10) in PHP.
Continue with a pattern that builds a number by reversing digits.
12 people found this page helpful