php GET and undefined index

Question

A new problem has arisen for me as I tried to run my script on a different PHP Server   ON my old server the following code appears to work fine - even when no s parameter is declared      lt  php  if    GET  s       jwshxnsyllabus   echo   lt body onload   loadSyllabi  syllabus       syllabi jwshxnporsyllabus xml               bibliographies jwshxnbibliography      gt    if    GET  s       aquinas   echo   lt body onload   loadSyllabi  syllabus       syllabi AquinasSyllabus xml     gt      if    GET  s       POP2   echo   lt body onload   loadSyllabi  POP2     gt    elseif    GET  s      null  echo   lt body gt     gt    But now  on a my local server on my local machine  XAMPP - Apache  I get the following error when no value for s is defined   Notice  Undefined index  s in C  xampp htdocs teaching index php on line 43 Notice  Undefined index  s in C  xampp htdocs teaching index php on line 45 Notice  Undefined index  s in C  xampp htdocs teaching index php on line 47 Notice  Undefined index  s in C  xampp htdocs teaching index php on line 49   What I want to happen for the script to call certain javascript functions if a value is declared for s  but if nothing is declared i would like the page to load normally    Can you help me

User · Answer

I recommend you check your arrays before you blindly access them :

if(isset($_GET['s'])){
    if ($_GET['s'] == 'jwshxnsyllabus')
        /* your code here*/
}

Another (quick) fix is to disable the error reporting by writing this on the top of the script :

error_reporting(0);

In your case, it is very probable that your other server had the error reporting configuration in php.ini set to 0 as default.
By calling the error_reporting with 0 as parameter, you are turning off all notices/warnings and errors. For more details check the php manual.

Remeber that this is a quick fix and it's highly recommended to avoid errors rather than ignore them.

User · Answer

Error reporting will have not included notices on the previous server which is why you haven t seen the errors   You should be checking whether the index s actually exists in the   GET array before attempting to use it   Something like this would be suffice   if  isset   GET  s           if    GET  s       jwshxnsyllabus           echo   lt body onload   loadSyllabi  syllabus       syllabi jwshxnporsyllabus xml               bibliographies jwshxnbibliography      gt        else if    GET  s       aquinas           echo   lt body onload   loadSyllabi  syllabus       syllabi AquinasSyllabus xml     gt         else if    GET  s       POP2           echo   lt body onload   loadSyllabi  POP2     gt      else       echo   lt body gt        It may be beneficial  if you plan on adding more cases  to use a switch statement to make your code more readable   switch   isset   GET  s        GET  s                case  jwshxnsyllabus           echo   lt body onload   loadSyllabi  syllabus       syllabi jwshxnporsyllabus xml               bibliographies jwshxnbibliography      gt            break      case  aquinas           echo   lt body onload   loadSyllabi  syllabus       syllabi AquinasSyllabus xml     gt            break      case  POP2           echo   lt body onload   loadSyllabi  POP2     gt            break      default          echo   lt body gt            break      EDIT  BTW  the first set of code I wrote mimics what yours is meant to do in it s entirety  Is the expected outcome of an unexpected value in  s  meant to output no  lt body gt  tag or was this an oversight  Note that the switch will fix this by always defaulting to  lt body gt

User · Answer

I was having the same problem in localhost with xampp  Now I m using this combination of parameters      Report all errors except E NOTICE    This is the default value set in php ini error reporting E ALL   E NOTICE     php net  http   php net manual pt BR function error-reporting php

User · Answer

The real answer to this is to put a   At symbol before the variable which will suppress the error     GET  field      POST  field     It will work some slower  but will keep the code clean   When something saves time for the programmer  and costs time for the website users  or requires more hardware   it depends on how much people will use it

User · Answer

Actually none of the proposed answers  although a good practice  would remove the warning   For the sake of correctness  I d do the following   function getParameter  param   defaultValue        if  array key exists  param    GET              value   GET  param           return isSet  value   value  defaultValue            return  defaultValue      This way  I check the  GET array for the key to exist without triggering the Warning  It s not a good idea to disable the warnings because a lot of times they are at least interesting to take a look   To use the function you just do    myvar   getParameter  getparamer    defaultValue     so if the parameter exists  you get the value  and if it doesnt  you get the defaultValue

User · Answer

Simple function  works with GET or POST  Plus you can assign a default value   function GetPost  var  default           return isset   GET  var       GET  var     isset   POST  var       POST  var     default

User · Answer

Get into the habit of checking if a variable is available with isset  e g   if  isset   GET  s              do stuff that requires  s    else          do stuff that doesn t need  s      You could disable notice reporting  but dealing them is good hygiene  and can allow you to spot problems you might otherwise miss

User · Answer

Another option would be to suppress the PHP undefined index notice with the   symbol in front of the GET variable like so    s      GET  s      This will disable the notice  It is better to check if the variable has been set and act accordingly    But this also works

User · Answer

First check the   GET  s   is set or not  Change your conditions like this   lt  php if  isset   GET  s     amp  amp    GET  s       jwshxnsyllabus   echo   lt body onload   loadSyllabi  syllabus       syllabi jwshxnporsyllabus xml               bibliographies jwshxnbibliography      gt    elseif  isset   GET  s     amp  amp    GET  s       aquinas   echo   lt body onload   loadSyllabi  syllabus       syllabi AquinasSyllabus xml     gt     elseif  isset   GET  s     amp  amp    GET  s       POP2   echo   lt body onload   loadSyllabi  POP2     gt    elseif  isset   GET  s     amp  amp    GET  s      null  echo   lt body gt     gt    And also handle properly your ifelse conditions

User · Answer

I always use a utility function class for reading from the   GET and   POST arrays to avoid having to always check the index exists    Something like this will do the trick   class Input   function get  name        return isset   GET  name       GET  name    null     function post  name        return isset   POST  name       POST  name    null     function get post  name        return  this- gt get  name     this- gt get  name     this- gt post  name        input   new Input   page    input- gt get post  page

User · Answer

You should check wheter the index exists before use it  compare it   if  isset   GET  s    AND   GET  s       foobar         echo  foo       Use E ALL   E STRICT while developing

User · Answer

Avoid if  else and elseifs    loadMethod       if isset   GET  s          switch   GET  s             case  jwshxnsyllabus                loadMethod    loadSyllabi  syllabus       syllabi jwshxnporsyllabus xml       bibliographies jwshxnbibliography              break          case  aquinas                loadMethod    loadSyllabi  syllabus       syllabi AquinasSyllabus xml             break          case  POP2                loadMethod    loadSyllabi  POP2              echo   lt body onload     loadMethod    gt      clean  readable code is maintainable code

[php] php $_GET and undefined index

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