Formatting A Number With Leading Zeros In PHP

<?php

#Ex:  Make 4 Digit Integer Or Zerofill An Integer In PHP

// INPUT

$start_number = 1;

$end_number = 100;

for($i=$start_number; $i <= $end_number; $i++ ){

    echo "<br> #: ".sprintf("%04d",  $i);  

}

// OUTPUT

#: 0001

#: 0002

#: 0003

#: 0004

#: 0005

#: 0006

#: 0007

#: 0008

#: 0009

#: 0010

.

.

.

#: 0100

?> 

According To Question:

#add zero after number in php

#php number format: 0001, 0002, 0003 ...

#make number 2 digit php

#php leftpad number

#php force two digit number

#php sprintf

#str_pad in php

#php left fill