What are the differences in die and exit in PHP

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

User · Answer

Something I have noticed in my scripts at least is that exit   will stop the currently executing script and pass control back to any calling script  while die will stop php in its tracks  I would say that is quite a big difference

User · Answer

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

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This page says die is an alies of exit  so they are identical  But also explains that      there are functions which changed names because of an API cleanup or some other reason and the old names are only kept as aliases for backward compatibility  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    So  call me paranoid  but there may be no dieing in the future

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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

User · Answer

Functionality-wise they are identical but I use them in the following scenarios to make code readable   Use die   when there is an error and have to stop the execution   e g  die   Oops  Something went wrong      Use exit   when there is not an error and have to stop the execution   e g  exit   Request has been processed successfully

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Here is something that s pretty interesting  Although exit   and die   are equivalent  die   closes the connection  exit   doesn t close the connection   die      lt  php     header  HTTP 1 1 304 Not Modified        die      gt    exit      lt  php     header  HTTP 1 1 304 Not Modified        exit      gt      Results   exit     HTTP 1 1 304 Not Modified  Connection  Keep-Alive  Keep-Alive  timeout 5  max 100   die     HTTP 1 1 304 Not Modified  Connection  close   Just incase in need to take this into account for your project   Credits  https   stackoverflow com a 20932511 4357238

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This output from https   3v4l org demonstrates that die and exit are functionally identical

User · Answer

They sound about the same  however  the exit   also allows you to set the exit code of your PHP script   Usually you don t really need this  but when writing console PHP scripts  you might want to check with for example Bash if the script completed everything in the right way   Then you can use exit   and catch that later on  Die   however doesn t support that   Die   always exists with code 0  So essentially a die   command does the following    lt  php echo  I am going to die   exit 0     gt    Which is the same as    lt  php die  I am going to die      gt

User · Answer

Functionally  they are identical  So to choose which one to use is totally a personal preference  Semantically in English  they are different  Die sounds negative  When I have a function which returns JSON data to the client and terminate the program  it can be awful if I call this function jsonDie    and it is more appropriate to call it jsonExit    For that reason  I always use exit instead of die

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From what I know when I look at this question here  It said there that  in PHP  there is a distinct difference in Header output  In the examples below I chose to use a different header but for sake of showing the difference between exit   and die   that doesn t matter   and tested  personally

User · Answer

As all the other correct answers says  die and exit are identical aliases   Although I have a personal convention that when I want to end the execution of a script when it is expected and desired  I use exit   And when I need to end the execution due to some problems  couldn t connect to db  can t write to file etc    I use die  Something went wrong     to  kill  the script   When I use exit   header   Location  http   www example com         Redirect browser       Make sure that code below does not get executed when we redirect     exit     I would like to end now    When I use die    data   file get contents   file txt     if   data     false         die   Failure         I don t want to end  but I can t continue  Die  script  Die    do something important   data      This way  when I see exit at some point in my code  I know that at this point I want to exit because the logic ends here  When I see die  I know that I d like to continue execution  but I can t or shouldn t due to error in previous execution   Of course this only works when working on a project alone  When there is more people nobody will prevent them to use die or exit where it does not fit my conventions

User · Answer

PHP manual on die      die     Equivalent to exit   You can even do die  the same way as exit  - with or without parens   The only advantage of choosing die   over exit    might be the time you spare on typing an extra letter  -

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They are essentially the same  though this article suggest otherwise

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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    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     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   quot 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  quot  But then I remembered we re in messy-syntax-land of PHP  In PHP  exit   and die   are identical  The designers obviously thought  quot 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  quot  The end result is that this didn t really make things any  quot easier quot   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  quot umm  two exit functions  which one should I use  quot  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

User · Answer

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

[php] What are the differences in die() and exit() in PHP?

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