exit, exit(), exit(0), die(), die(0) - How to exit script

Question

I believe that all of these (and even die() or die(0)) are identical. If they are not identical, which is preferred for exiting a script successfu

Answer 1

These are all identical. I'm pretty sure die() is just a straight-up alias to exit(), but even if it isn't, it still acts identically.

When one of these functions is given a string argument, it prints out the string before terminating the process. When it encounters an integer under 255, that integer is considered the return code for the process, which gets passed back to the process which invoked the PHP script. This is particularly useful when writing command line applications (PHP isn't web-only!).

As far as the difference between exit, exit(), and exit(0), there really is none. There is definitely no difference between the first two because exit is technically a language construct, not a function, so it can be called with or without parentheses, just like echo. Returning a code of 0 means "this program ran successfully/without errors", and while I don't know what exactly happens when you don't pass an argument, PHP.net says that an argument-less exit indicates success, so I would bet it returns 0, though again PHP.net doesn't show a default for the argument.