Notice Undefined variable Notice Undefined index and Notice Undefined offset using PHP

Question

I m running a PHP script and continue to receive errors like   Notice  Undefined variable  my variable name in C  wamp www mypath index php on line 10 Notice  Undefined index  my index C  wamp www mypath index php on line 11  Line 10 and 11 looks like this  echo  quot My variable value is   quot     my variable name  echo  quot My index value is   quot     my array  quot my index quot     What is the meaning of these error messages  Why do they appear all of a sudden  I used to use this script for years and I ve never had any problem  How do I fix them    This is a General Reference question for people to link to as duplicate  instead of having to explain the issue over and over again  I feel this is necessary because most real-world answers on this issue are very specific   Related Meta discussion   What can be done about repetitive questions  Do    reference questions    make sense

User · Answer

One common cause of a variable not existing after an HTML form has been submitted is the form element is not contained within a <form> tag:

Example: Element not contained within the <form>

<form action="example.php" method="post">
    <p>
        <input type="text" name="name" />
        <input type="submit" value="Submit" />
    </p>
</form>

<select name="choice">
    <option value="choice1">choice 1</option>
    <option value="choice2">choice 2</option>
    <option value="choice3">choice 3</option>
    <option value="choice4">choice 4</option>
</select>

Example: Element now contained within the <form>

<form action="example.php" method="post">
    <select name="choice">
        <option value="choice1">choice 1</option>
        <option value="choice2">choice 2</option>
        <option value="choice3">choice 3</option>
        <option value="choice4">choice 4</option>
    </select>
    <p>
        <input type="text" name="name" />
        <input type="submit" value="Submit" />
    </p>
</form>

User · Answer

Using a ternary is simple  readable  and clean   Pre PHP 7 Assign a variable to the value of another variable if it s set  else assign null  or whatever default value you need       newVariable   isset  thePotentialData     thePotentialData   null    PHP 7  The same except using Null Coalescing Operator  There s no longer a need to call isset   as this is built in  and no need to provide the variable to return as it s assumed to return the value of the variable being checked      newVariable    thePotentialData    null    Both will stop the Notices from the OP question  and both are the exact equivalent of   if  isset  thePotentialData          newVariable    thePotentialData    else        newVariable   null       nbsp  If you don t require setting a new variable then you can directly use the ternary s returned value  such as with echo  function arguments  etc   Echo     echo  Your name is      isset  name     name    You did not provide one     Function      foreName   getForeName isset  userId     userId   null    function getForeName  userId        if   userId     null               Etc           The above will work just the same with arrays  including sessions etc  replacing the variable being checked with e g     SESSION  checkMe   or however many levels deep you need  e g    clients  personal    address    postcode       nbsp     Suppression     It is possible to suppress the PHP Notices with   or reduce your error reporting level  but it does not fix the problem  it simply stops it being reported in the error log  This means that your code still tried to use a variable that was not set  which may or may not mean something doesn t work as intended - depending on how crucial the missing value is     You should really be checking for this issue and handling it appropriately  either serving a different message  or even just returning a null value for everything else to identify the precise state   If you just care about the Notice not being in the error log  then as an option you could simply ignore the error log

User · Answer

I use all time own useful function exst   which automatically declare variables   Your code will be -   greeting    Hello    exst  user name   Visitor     from   exst  user location             Function exst   - Checks if the variable has been set      copy paste it in any place of your code         If the variable is set and not empty returns the variable  no transformation     If the variable is not set or empty  returns the  default value        param  mixed  var     param  mixed  default         return mixed       function exst   amp   var   default              t           if    isset  var        var             if  isset  default   amp  amp   default         t    default            else               t    var            if  is string  t    t   trim  t       return  t

User · Answer

I used to curse this error  but it can be helpful to remind you to escape user input   For instance  if you thought this was clever  shorthand code      Echo whatever the hell this is  lt     POST  something    gt       Think again  A better solution is      If this is set  echo a filtered version  lt   isset   POST  something      html   POST  something          gt     I use a custom html   function to escape characters  your mileage may vary

User · Answer

Another reason why an undefined index notice will be thrown  would be that a column was omitted from a database query   I e     query    SELECT col1 FROM table WHERE col x         Then trying to access more columns rows inside a loop   I e    print r  row  col1     print r  row  col2        undefined index thrown   or in a while loop   while   row   fetching function  query           echo  row  col1        echo   lt br gt        echo  row  col2       undefined index thrown     echo   lt br gt        echo  row  col3       undefined index thrown      Something else that needs to be noted is that on a  NIX OS and Mac OS X  things are case-sensitive   Consult the followning Q amp A s on Stack    Are table names in MySQL case sensitive  mysql case sensitive table names in queries MySql - Case Sensitive issue of tables in different server

User · Answer

If working with classes you need to make sure you reference member variables using  this   class Person       protected  firstName      protected  lastName       public function setFullName  first   last                   Correct          this- gt firstName    first              Incorrect          lastName    last              Incorrect          this- gt  lastName    last

User · Answer

Try these     Q1  this notice means  varname is not   defined at current scope of the   script       Q2  Use of isset    empty   conditions before using any suspicious variable works well       recommended solution for recent PHP versions  user name     SESSION  user name              pre-7 PHP versions  user name       if   empty   SESSION  user name             user name     SESSION  user name        Or  as a quick and dirty solution       not the best solution  but works    in your php setting use  it helps hiding site wide notices error reporting E ALL   E NOTICE       Note about sessions    When using sessions  session start    is required to be placed inside all files using sessions  http   php net manual en features sessions php

User · Answer

When dealing with files  a proper enctype and a POST method are required  which will trigger an undefined index notice if either are not included in the form   The manual states the following basic syntax   HTML   lt  -- The data encoding type  enctype  MUST be specified as below -- gt   lt form enctype  multipart form-data  action    URL    method  POST  gt       lt  -- MAX FILE SIZE must precede the file input field -- gt       lt input type  hidden  name  MAX FILE SIZE  value  30000    gt       lt  -- Name of input element determines name in   FILES array -- gt      Send this file   lt input name  userfile  type  file    gt       lt input type  submit  value  Send File    gt   lt  form gt    PHP   lt  php    In PHP versions earlier than 4 1 0   HTTP POST FILES should be used instead    of   FILES    uploaddir     var www uploads     uploadfile    uploaddir   basename   FILES  userfile    name      echo   lt pre gt    if  move uploaded file   FILES  userfile    tmp name     uploadfile         echo  File is valid  and was successfully uploaded  n     else       echo  Possible file upload attack  n      echo  Here is some more debugging info    print r   FILES    print   lt  pre gt       gt    Reference    http   php net manual en features file-upload post-method php

User · Answer

Its because the variable    user location  is not getting defined  If you are using any if loop inside which you are declaring the   user location  variable then you must also have an else loop and define the same  For example    a 10  if  a  5     user location  Paris    else     echo  user location    The above code will create error as The if loop is not satisfied and in the else loop   user location  was not defined  Still PHP was asked to echo out the variable  So to modify the code you must do the following    a 10  if  a  5     user location  Paris    else    user location  SOMETHING OR BLANK     echo  user location

User · Answer

Error display   operator  For undesired and redundant notices  one could use the dedicated   operator to   hide   undefined variable index messages    var       GET  optional param        This is usually discouraged  Newcomers tend to way overuse it  It s very inappropriate for code deep within the application logic  ignoring undeclared variables where you shouldn t   e g  for function parameters  or in loops  There s one upside over the isset   or    super-supression however  Notices still can get logged  And one may resurrect  -hidden notices with  set error handler  var dump      Additonally you shouldn t habitually use recommend if  isset   POST  shubmit     in your initial code  Newcomers won t spot such typos  It just deprives you of PHPs Notices for those very cases  Add   or isset only after verifying functionality     Fix the cause first  Not the notices      is mainly acceptable for   GET   POST input parameters  specifically if they re optional    And since this covers the majority of such questions  let s expand on the most common causes     GET     POST     REQUEST undefined input   First thing you do when encountering an undefined index offset  is check for typos      count     GET  whatnow       Is this an expected key name and present on each page request  Variable names and array indicies are case-sensitive in PHP   Secondly  if the notice doesn t have an obvious cause  use  var dump or print r to verify all input arrays for their curent content   var dump   GET   var dump   POST     print r   REQUEST     Both will reveal if your script was invoked with the right or any parameters at all  Alternativey or additionally use your browser devtools  F12  and inspect the network tab for requests and parameters     POST parameters and GET input will be be shown separately  For   GET parameters you can also peek at the QUERY STRING in  print r   SERVER     PHP has some rules to coalesce non-standard parameter names into the superglobals  Apache might do some rewriting as well   You can also look at supplied raw   COOKIES and other HTTP request headers that way  More obviously look at your browser address bar for GET parameters   http   example org script php id 5 amp sort desc  The name value pairs after the   question mark are your query  GET  parameters  Thus this URL could only possibly yield   GET  id   and   GET  sort    Finally check your  lt form gt  and  lt input gt  declarations  if you expect a parameter but receive none    Ensure each required input has an  lt input name FOO gt  The id  or title  attribute does not suffice  A method POST form ought to populate   POST  Whereas a method GET  or leaving it out  would yield   GET variables  It s also possible for a form to supply action script php get param via   GET and the remaining method POST fields in   POST alongside  With modern PHP configurations    5 6  it has become feasible  not fashionable  to use   REQUEST  vars   again  which mashes GET and POST params   If you are employing mod rewrite  then you should check both the access log as well as enable the RewriteLog to figure out absent parameters      FILES   The same sanity checks apply to file uploads and   FILES  formname    Moreover check for enctype multipart form-data As well as method POST in your  lt form gt  declaration  See also  PHP Undefined index error   FILES      COOKIE   The   COOKIE array is never populated right after setcookie    but only on any followup HTTP request  Additionally their validity times out  they could be constraint to subdomains or individual paths  and user and browser can just reject or delete them

User · Answer

Notice  Undefined variable  From the vast wisdom of the PHP Manual      Relying on the default value of an uninitialized variable is problematic in the case of including one file into another which uses the same variable name  It is also a major security risk with register globals turned on  E NOTICE level error is issued in case of working with uninitialized variables  however not in the case of appending elements to the uninitialized array  isset   language construct can be used to detect if a variable has been already initialized  Additionally and more ideal is the solution of empty   since it does not generate a warning or error message if the variable is not initialized     From PHP documentation      No warning is generated if the variable does not exist  That means      empty   is essentially the concise equivalent to  isset  var      var         false    This means that you could use only empty   to determine if the variable is set  and in addition it checks the variable against the following  0  0 0       0   null  false or      Example      o         var       0 null 1 2 3  foo  o  myIndex     array walk  var  function  v        echo   isset  v      v    false     true      false       echo        empty  v     true     false        echo   n         Test the above snippet in the 3v4l org online PHP editor  Although PHP does not require a variable declaration  it does recommend it in order to avoid some security vulnerabilities or bugs where one would forget to give a value to a variable that will be used later in the script  What PHP does in the case of undeclared variables is issue a very low level error  E NOTICE  one that is not even reported by default  but the Manual advises to allow during development   Ways to deal with the issue    Recommended  Declare your variables  for example when you try to append a string to an undefined variable  Or use isset      empty    to check if they are declared before referencing them  as in     Initializing variable  value         Initialization value  Examples                   When you want to append stuff later                0  When you want to add numbers later   isset    value   isset   POST  value        POST  value           empty    value    empty   POST  value        POST  value           This has become much cleaner as of PHP 7 0  now you can use the null coalesce operator      Null coalesce operator - No need to explicitly initialize the variable   value     POST  value           Set a custom error handler for E NOTICE and redirect the messages away from the standard output  maybe to a log file      set error handler  myHandlerForMinorErrors   E NOTICE   E STRICT   Disable E NOTICE from reporting  A quick way to exclude just E NOTICE is   error reporting  error reporting    amp   E NOTICE    Suppress the error with the   operator    Note  It s strongly recommended to implement just point 1   Notice  Undefined index   Undefined offset  This notice appears when you  or PHP  try to access an undefined index of an array   Ways to deal with the issue    Check if the index exists before you access it  For this you can use isset   or array key exists       isset    value   isset  array  my index       array  my index           array key exists    value   array key exists  my index    array     array  my index          The language construct list   may generate this when it attempts to access an array index that does not exist   list  a   b    array 0   gt   a      or list  one   two    explode       test string       Two variables are used to access two array elements  however there is only one array element  index 0  so this will generate      Notice  Undefined offset  1     POST     GET     SESSION variable  The notices above appear often when working with   POST    GET or   SESSION  For   POST and   GET you just have to check if the index exists or not before you use them  For   SESSION you have to make sure you have the session started with session start   and that the index also exists   Also note that all 3 variables are superglobals and are uppercase   Related    Notice  Undefined variable Notice  Undefined Index

User · Answer

In PHP you need fist to define the variable after that you can use it  We can check variable is defined or not in very efficient way      If you only want to check variable has value and value has true and false value    But variable must be defined first   if  my variable name         If you want to check variable is define or undefine   Isset   does not check that variable has true or false value   But it check null value of variable if isset  my variable name         Simple Explanation    It will work with  - true false NULL  defineVarialbe   false  if  defineVarialbe       echo  true    else      echo  false        It will check variable is define or not and variable has null value  if isset  unDefineVarialbe        echo  true    else      echo  false

User · Answer

It means you are testing  evaluating  or printing a variable that you have not yet assigned anything to   It means you either have a typo  or you need to check that the variable was initialized to something first   Check your logic paths  it may be set in one path but not in another

User · Answer

In a very Simple Language  The mistake is you are using a variable  user location which is not defined by you earlier and it doesn t have any value So I recommend you to please declare this variable before using it  For Example    user location      Or  user location    Los Angles   This is a very common error you can face So don t worry just declare the variable and Enjoy Coding

User · Answer

undefined index means in an array you requested for unavailable array index for example    lt  php    newArray      1 2 3 4 5   print r  newArray 5       gt    undefined variable means you have used completely not existing variable or which is not defined or initialized by that name for example    lt  php print r  myvar     gt    undefined offset means in array you have asked for non existing key  And the  solution for this is to check before use   php gt  echo array key exists 1   myarray

User · Answer

In reply to   Why do they appear all of a sudden  I used to use this script for years and I ve never had any problem     It is very common for most sites to operate under the  default  error reporting of  Show all errors  but not  notices  and  deprecated    This will be set in php ini and apply to all sites on the server  This means that those  notices  used in the examples will be suppressed  hidden  while other errors  considered more critical  will be shown recorded   The other critical setting is the errors can be hidden  i e  display errors set to  off  or  syslog      What will have happened in this case is that either the error reporting was changed to also show notices  as per examples  and or that the settings were changed to display errors on screen  as opposed to suppressing them logging them    Why have they changed   The obvious simplest answer is that someone adjusted either of these settings in php ini  or an upgraded version of PHP is now using a different php ini from before  That s the first place to look   However it is also possible to override these settings in    htconf   webserver configuration  including vhosts and sub-configurations    htaccess in php code itself   and any of these could also have been changed   There is also the added complication that the web server configuration can enable disable  htaccess directives  so if you have directives in  htaccess that suddenly start stop working then you need to check for that     htconf    htaccess assume you re running as apache  If running command line this won t apply  if running IIS or other webserver then you ll need to check those configs accordingly   Summary   Check error reporting and display errors php directives in php ini has not changed  or that you re not using a different php ini from before  Check error reporting and display errors php directives in  htconf  or vhosts etc  have not changed Check error reporting and display errors php directives in  htaccess have not changed If you have directive in  htaccess  check if they are still permitted in the  htconf file Finally check your code  possibly an unrelated library  to see if error reporting and display errors php directives have been set there

User · Answer

why not keep things simple    lt  php error reporting E ALL      making sure all notices are on  function idxVal  amp  var   default   null             return empty  var     var    default    var       echo idxVal  arr  test                returns null without any notice echo idxVal  arr  hey ho     yo       returns yo and assigns it to array index  nice    gt

User · Answer

I didn t want to disable notice because it s helpful  but wanted to avoid too much typing    My solution was this function   function ifexists  varname      return isset   varname   varname null       So if I want to reference to  name and echo if exists  I simply write    lt   ifexists  name    gt    For array elements   function ifexistsidx  var  index      return isset  var  index    var  index  null       In page if I want to refer to   REQUEST  name      lt   ifexistsidx   REQUEST  name    gt

User · Answer

Probably you were using old PHP version until and now upgraded PHP thats the reason it was working without any error till now from years  until PHP4 there was no error if you are using variable without defining it but as of PHP5 onwards it throws errors for codes like mentioned in question

User · Answer

Those notices are because you don t have the used variable defined and my index key was not present into  my array variable    Those notices were triggered every time  because your code is not correct  but probably you didn t have the reporting of notices on   Solve the bugs    my variable name    Variable name      defining variable echo  My variable value is       my variable name   if isset  my array  my index          echo  My index value is       my array  my index       check if my index is set      Another way to get this out   ini set  error reporting   false

User · Answer

WHY IS THIS HAPPENING   Over time  PHP has become a more security-focused language  Settings which used to be turned off by default are now turned on by default  A perfect example of this is E STRICT  which became turned on by default as of PHP 5 4 0    Furthermore  according to PHP documentation  by default  E NOTICE is disabled in php ini  PHP docs recommend turning it on for debugging purposes  However  when I download PHP from the Ubuntu repository   and from BitNami s Windows stack   I see something else     Common Values      E ALL  Show all errors  warnings and notices including coding standards       E ALL  amp   E NOTICE   Show all errors  except for notices      E ALL  amp   E NOTICE  amp   E STRICT   Show all errors  except for notices and coding standards warnings       E COMPILE ERROR E RECOVERABLE ERROR E ERROR E CORE ERROR   Show only errors    Default Value  E ALL  amp   E NOTICE  amp   E STRICT  amp   E DEPRECATED   Development Value  E ALL   Production Value  E ALL  amp   E DEPRECATED  amp   E STRICT   http   php net error-reporting error reporting   E ALL  amp   E DEPRECATED  amp   E STRICT   Notice that error reporting is actually set to the production value by default  not to the  default  value by default  This is somewhat confusing and is not documented outside of php ini  so I have not validated this on other distributions   To answer your question  however  this error pops up now when it did not pop up before because    You installed PHP and the new default settings are somewhat poorly documented but do not exclude E NOTICE  E NOTICE warnings like undefined variables and undefined indexes actually help to make your code cleaner and safer  I can tell you that  years ago  keeping E NOTICE enabled forced me to declare my variables  It made it a LOT easier to learn C  were not declaring variables is much bigger of a nuisance     WHAT CAN I DO ABOUT IT    Turn off E NOTICE by copying the  Default value  E ALL  amp   E NOTICE  amp   E STRICT  amp   E DEPRECATED and replacing it with what is currently uncommented after the equals sign in error reporting    Restart Apache  or PHP if using CGI or FPM  Make sure you are editing the  right  php ini  The correct one will be Apache if you are running PHP with Apache  fpm or php-fpm if running PHP-FPM  cgi if running PHP-CGI  etc  This is not the recommended method  but if you have legacy code that s going to be exceedingly difficult to edit  then it might be your best bet  Turn off E NOTICE on the file or folder level  This might be preferable if you have some legacy code but want to do things the  right  way otherwise  To do this  you should consult Apache2  Nginx  or whatever your server of choice is  In Apache  you would use php value inside of  lt Directory gt   Rewrite your code to be cleaner  If you need to do this while moving to a production environment or don t want someone to see your errors  make sure you are disabling any display of errors  and only logging your errors  see display errors and log errors in php ini and your server settings     To expand on option 3  This is the ideal  If you can go this route  you should  If you are not going this route initially  consider moving this route eventually by testing your code in a development environment  While you re at it  get rid of  E STRICT and  E DEPRECATED to see what might go wrong in the future  You re going to see a LOT of unfamiliar errors  but it s going to stop you from having any unpleasant problems when you need to upgrade PHP in the future   WHAT DO THE ERRORS MEAN   Undefined variable  my variable name - This occurs when a variable has not been defined before use  When the PHP script is executed  it internally just assumes a null value  However  in which scenario would you need to check a variable before it was defined  Ultimately  this is an argument for  sloppy code   As a developer  I can tell you that I love it when I see an open source project where variables are defined as high up in their scopes as they can be defined  It makes it easier to tell what variables are going to pop up in the future and makes it easier to read learn the code   function foo          my variable name                        if   my variable name               perform some logic           Undefined index  my index - This occurs when you try to access a value in an array and it does not exist  To prevent this error  perform a conditional check      verbose way - generally better if  isset  my array  my index           echo  My index value is       my array  my index          non-verbose ternary example - I use this sometimes for small rules   my index val   isset  my array  my index     my array  my index     undefined    echo  My index value is       my index val       Another option is to declare an empty array at the top of your function  This is not always possible    my array   array       my index    gt                 my array  my index      new string      additional tip    When I was encountering these and other issues  I used NetBeans IDE  free  and it gave me a host of warnings and notices  Some of them offer very helpful tips  This is not a requirement  and I don t use IDEs anymore except for large projects  I m more of a vim person these days

User · Answer

These errors occur whenever we are using a variable that is not set   The best way to deal with these is set error reporting on while development   To set error reporting on   ini set  error reporting    on    ini set  display errors    on    error reporting E ALL     On production servers  error reporting is off  therefore  we do not get these errors   On the development server  however  we can set error reporting on   To get rid of this error  we see the following example   if   my    9      test    yes       Will produce error as  my is not 9    echo  test    We can initialize the variables to NULL before assigning their values or using them   So  we can modify the code as    test   NULL  if   my    9      test    yes       Will produce error as  my is not 9    echo  test    This will not disturb any program logic and will not produce Notice even if  test does not have value   So  basically  its always better to set error reporting ON for development   And fix all the errors   And on production  error reporting should be set to off

User · Answer

In PHP 7 0 it s now possible to use Null coalescing operator   echo  My index value is        my array  my index             Equals to   echo  My index value is       isset  my array  my index       my array  my index            PHP manual PHP 7 0

User · Answer

I asked a question about this and I was referred to this post with the message      This question already has an answer here          Notice  Undefined variable        Notice  Undefined index     and    Notice    Undefined offset    using PHP   I am sharing my question and solution here   This is the error     Line 154 is the problem  This is what I have in line 154   153    foreach  cities as  key   gt   city   154        if   city     London    amp  amp    city     Madrid    amp  amp    citiesCounterArray  key   gt   1      I think the problem is that I am writing if conditions for the variable  city  which is not the key but the value in  key   gt   city  First  could you confirm if that is the cause of the warning  Second  if that is the problem  why is it that I cannot write a condition based on the value  Does it have to be with the key that I need to write the condition   UPDATE 1  The problem is that when executing  citiesCounterArray  key   sometimes the  key corresponds to a key that does not exist in the  citiesCounterArray array  but that is not always the case based on the data of my loop  What I need is to set a condition so that if  key exists in the array  then run the code  otherwise  skip it   UPDATE 2  This is how I fixed it by using array key exists     foreach  cities as  key   gt   city       if array key exists  key   citiesCounterArray            if   city     London    amp  amp    city     Madrid    amp  amp    citiesCounterArray  key   gt   1

User · Answer

the quick fix is to assign your variable to null at the top of your code   user location   null

User · Answer

The best way for getting input string is    value   filter input INPUT POST   value      This one-liner is almost equivalent to   if   isset   POST  value            value   null    elseif  is array   POST  value            value   false    else        value     POST  value        If you absolutely want string value  just like    value    string filter input INPUT POST   value

User · Answer

Generally because of  bad programming   and a possibility for mistakes now or later    If it s a mistake  make a proper assignment to the variable first    varname 0  If it really is only defined sometimes  test for it   if  isset  varname    before using it If it s because you spelled it wrong  just correct that Maybe even turn of the warnings in you PHP-settings

User · Answer

Regarding this part of the question      Why do they appear all of a sudden  I used to use this script for years and I ve never had any problem    No definite answers but here are a some possible explanations of why settings can  suddenly  change    You have upgraded PHP to a newer version which can have other defaults for error reporting  display errors or other relevant settings  You have removed or introduced some code  possibly in a dependency  that sets relevant settings at runtime using ini set   or error reporting    search for these in the code  You changed the webserver configuration  assuming apache here    htaccess files and vhost configurations can also manipulate php settings  Usually notices don t get displayed   reported  see PHP manual  so it is possible that when setting up the server  the php ini file could not be loaded for some reason  file permissions    and you were on the default settings  Later on  the  bug  has been solved  by accident  and now it CAN load the correct php ini file with the error reporting set to show notices

[php] "Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset" using PHP

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