As myself, you might be super familiar with the increment/decrement operator e.g.

++$i # vs$i++


What was new to me, was that you can pre or post incrememnt, depending how you need it to behave!

Now, what’s the difference?

$i = 0 do{$i
}
while(
$i++ -le 5 ) # Output: 0123456  $i = 0

do{
$i } while( ++$i -le 5
)

# Output:
012345


It basically dictates the behaviour of when the actual incementation is happening, BEFORE (pre-increment) the eval or AFTER (post-increment)

Reference