What are some limitations of PHP?
Recently I answered a question on quora. I am reproducing it here again.
In my view question is not complete and does not provide context which has to be evaluated to answer.
So I am writing this answer based on two assumptions.
First of all I am assuming that questioner is evaluating few programming languages and wants to make a decision which language to use or learn?
One of the major feature of PHP is also its biggest limitation. It is loose type and does automatic data type conversion in most of the situations. It does not force you to be good. You can easily write a bad code and it will not give you any warning or notice, but this does not mean that you can not write good code in PHP. So if you ever found a good PHP programmer, praise him/her because he/she is doing good programming without being under a hunter of strict compiler or interpreter.
PHP is more suitable for web development and shell scripts (yes it is quite good at command prompt also). You should not consider this for desktop applications. PHP-GTK is available but still far away from being productive. So one limitation is lack of desktop application development support. You can also not do mobile programming although you can run PHP on an Android device start [PHP for Android]
PHP supports almost all good features and data types but it does not force you to use them (.. and falls back to default behavior) which sometimes can be source of bug introduction in your applications.
As far as leaning is concerned, PHP is easy but I will suggest learning another strong typed language like C or Java along with PHP (at least basic knowledge must be there) if you really wants to go to a good level in programming.
Second assumptions, I am making that questioner wants to gather points to do fight with the PHP guy on the block, in that case I would suggest, Please do not waste your time, No language is without some shortcomings in some specific context.
So choose your language based on your need. PHP is best in some cases and worst in some cases
PHP is growing and is on a fast lane in new features introduction, so we can hope that it will extends its reach to more different verticals in near future.