What are the differences in die() and exit() in PH

Question

What are the differences between die() and exit() functions in PHP?

I think both have the same functionality, but I doubt there is something different in both... what is it?

Answer 1

There's no difference - they are the same.

PHP Manual for exit:

Note: This language construct is equivalent to die().

PHP Manual for die:

This language construct is equivalent to exit().

Answer 2

As stated before, these two commands produce the same parser token.

BUT

There is a small difference, and that is how long it takes the parser to return the token.

I haven't studied the PHP parser, but if it's a long list of functions starting with "d", and a shorter list starting with "e", then there must be a time penalty looking up the function name for functions starting with "e". And there may be other differences due to how the whole function name is checked.

I doubt it will be measurable unless you have a "perfect" environment dedicated to parsing PHP, and a lot of requests with different parameters. But there must be a difference, after all, PHP is an interpreted language.

Answer 3

The result of exit() function and die() function is allways same. But as explained in alias manual page (http://php.net/manual/en/aliases.php), it says that die() function calls exit function. I think it is hard coded like below:

function die($msg){
  exit($msg);
}

This is not a performance issue for small, medium and large projects but if project has billions multiply billions multiply billions processes, this happens very important performance optimization state.

But very most of people don't thinks this is a problem, because if you have that much processes, you must think more problem than if a function is master or alias.

But, exact answer is that; allways master function is more faster than alias.

Finally; Alias manual page says that, you may no longer use die. It is only an alias, and it is deprecated.

It is usually a bad idea to use these kind of aliases, as they may be bound to obsolescence or renaming, which will lead to unportable script. This list is provided to help those who want to upgrade their old scripts to newer syntax.

Answer 4

DIFFERENCE IN ORIGIN

The difference between die() and exit() in PHP is their origin.

• exit() is from exit() in C.
• die() is from die in Perl.

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FUNCTIONALLY EQUIVALENT

die() and exit() are equivalent functions.

PHP Manual

PHP Manual for die:

This language construct is equivalent to exit().

PHP Manual for exit:

Note: This language construct is equivalent to die().

PHP Manual for List of Function Aliases:

die is an alias for master function exit()

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DIFFERENT IN OTHER LANGUAGES

die() and exit() are different in other languages but in PHP they are identical.

From Yet another PHP rant:

...As a C and Perl coder, I was ready to answer, "Why, exit() just bails off the program with a numeric exit status, while die() prints out the error message to stderr and exits with EXIT_FAILURE status." But then I remembered we're in messy-syntax-land of PHP.

In PHP, exit() and die() are identical.

The designers obviously thought "Hmm, let's borrow exit() from C. And Perl folks probably will like it if we take die() as is from Perl too. Oops! We have two exit functions now! Let's make it so that they both can take a string or integer as an argument and make them identical!"

The end result is that this didn't really make things any "easier", just more confusing. C and Perl coders will continue to use exit() to toss an integer exit value only, and die() to toss an error message and exit with a failure. Newbies and PHP-as-a-first-language people will probably wonder "umm, two exit functions, which one should I use?" The manual doesn't explain why there's exit() and die().

In general, PHP has a lot of weird redundancy like this - it tries to be friendly to people who come from different language backgrounds, but while doing so, it creates confusing redundancy.

Answer 5

They are essentially the same, though this article suggest otherwise.