Convert 1 digit number to HH:mm:ss format in PHP

Question

In PHP, how do I convert a 1-digit number to a full time representation, for example:

0
1
2
...
17
18
19

Convert to a complete time representation, for example:

00:00:00
01:00:00
02:00:00
...
17:00:00
18:00:00
19:00:00

I tried using the strtotime() and date() functions but didn't really grasp their usage.

Answer 1

Use sprintf to zero-fill to two digits:

foreach (range(0, 23) as $i) {
   echo sprintf('%02d:00:00' . PHP_EOL, $i);
}