How is this the output of the code

Question

How is this the output of the code
https://code.sololearn.com/wDgV4FWh2g9E/?ref=app

Answer 1

The simplified code will be like

$a=1;
echo $a;
$a = $a+1;

$a = $a+1;
echo $a;

In post-increment returns the original value before it changes the variable, while the pre-increment changes the variable first and then return the value.

ref: https://www.sololearn.com/learn/PHP/1803/