What is the deifference between Post Increment and Pre Increment?

[phpcharan]

What is the deifference between Post Increment and Pre Increment?

and how they are useful?

 

[GingerRobot]

Try running the following two code snippets:

 

$foo = 6;
$bar = 5;

if($foo == $bar++){
echo 'True. Foo:'.$foo.' Bar:'.$bar;
}else{
echo 'False. Foo:'.$foo.' Bar:'.$bar;
}

 

$foo = 6;
$bar = 5;

if($foo == ++$bar){
echo 'True. Foo:'.$foo.' Bar:'.$bar;
}else{
echo 'False. Foo:'.$foo.' Bar:'.$bar; 
}

 

As you will see, in both cases, after the if statement, both $foo and $bar are 6. However, only the if statement in the second code snippet is true. That is because $bar is incremented prior to being tested for equality.