Number of digits ?

[MichaelHe]

I have a variabling number that sometimes i below 10 and sometimes more than 10.

How do I echo it so it will always be written as 2 digits.
01 02 03 ... 08 09 10 11 12 and so on. ?

[devinemke]

$i = 2;
echo sprintf('%02s', $i);

[_theworks]

or,

$i = 3;
echo str_pad($i, 2, "0", STR_PAD_LEFT);