How to get a variable name as a string in PHP

Question

Say i have this PHP code    FooBar    a string     i then need a function like this   print var name  FooBar     which prints   FooBar   Any Ideas how to achieve this  Is this even possible in PHP

User · Answer

I was looking for this but just decided to pass the name in  I usually have the name in the clipboard anyway   function VarTest  my var  my var name       echo      my var name       my var   lt br   gt        fruit  apple   VarTest  fruit  fruit

User · Answer

If the variable is interchangable  you must have logic somewhere that s determining which variable gets used  All you need to do is put the variable name in  variable within that logic while you re doing everything else   I think we re all having a hard time understanding what you re needing this for  Sample code or an explanation of what you re actually trying to do might help  but I suspect you re way  way overthinking this

User · Answer

I really fail to see the use case    If you will type print var name  foobar  what s so hard  and different  about typing print  foobar   instead    Because even if you were to use this in a function  you d get the local name of the variable     In any case  here s the reflection manual in case there s something you need in there

User · Answer

Use this to detach user variables from global to check variable at the moment     function get user var defined           return array slice  GLOBALS 8 count  GLOBALS -8           function get var name   var          vuser   get user var defined         foreach  vuser as  key  gt  value                 if  var    value  return  key

User · Answer

Adapted from answers above for many variables  with good performance  just one  GLOBALS scan for many  function compact assoc  amp  v1    undefined      amp  v2    undefined     amp  v3    undefined     amp  v4    undefined     amp  v5    undefined     amp  v6    undefined     amp  v7    undefined     amp  v8    undefined     amp  v9    undefined     amp  v10    undefined     amp  v11    undefined     amp  v12    undefined     amp  v13    undefined     amp  v14    undefined     amp  v15    undefined     amp  v16    undefined     amp  v17    undefined     amp  v18    undefined     amp  v19    undefined             defined vars get defined vars          result Array         reverse key Array         original value Array        foreach   defined vars as  source key   gt   source value           if  source value      undefined     break           original value  source key    source key           new test value  PREFIX  rand    SUFIX            reverse key  new test value   source key            source key  new test value             foreach  GLOBALS as  key   gt   amp  value           if  is string  value   amp  amp  isset  reverse key  value                     result  key   amp  value                      foreach   original value as  source key   gt   original value             source key  original value            return  result       a    A    b    B    c    999    myArray Array   id   gt  id123   name   gt  Foo    print r compact assoc  a  b  c  myArray        print Array        a    gt  A      b    gt  B      c    gt  999      myArray    gt  Array                        id    gt  id123              name    gt  Foo

User · Answer

There is no predefined function in PHP that can output the name of a variable  However  you can use the result of get defined vars    which returns all the variables defined in the scope  including name and value  Here is an example   lt  php        Function for determining the name of a variable     function getVarName  amp  var   definedVars null             definedVars     is array  definedVars     GLOBALS    definedVars            val    var           rand   1          while  in array  rand   definedVars  true                  rand   md5 mt rand 10000  1000000                       var    rand                    foreach   definedVars as  dvName  gt  dvVal                if   dvVal      rand                     var    val                  return  dvName                                            return null                 the name of  a is to be determined          a   1               Determine the name of  a     echo getVarName  a     gt   Read more in How to get a variable name as a string in PHP

User · Answer

You might consider changing your approach and using a variable variable name    var name    FooBar     var name    a string     then you could just   print  var name     to get   FooBar   Here s the link to the PHP manual on Variable variables

User · Answer

I really fail to see the use case    If you will type print var name  foobar  what s so hard  and different  about typing print  foobar   instead    Because even if you were to use this in a function  you d get the local name of the variable     In any case  here s the reflection manual in case there s something you need in there

User · Answer

You could use compact   to achieve this    FooBar    a string     newArray   compact  FooBar      This would create an associative array with the variable name as the key   You could then loop through the array using the key name where you needed it   foreach  newarray as  key   gt   value        echo  key

User · Answer

Many replies question the usefulness of this  However  getting a reference for a variable can be very useful  Especially in cases with objects and  this  My solution works with objects  and as property defined objects as well   function getReference  amp  var        if is object  var            var- gt    uniqid   uniqid        else          var   serialize  var        name   getReference traverse  var  GLOBALS       if is object  var           unset  var- gt    uniqid       else          var   unserialize  var       return      name           function getReference traverse  amp  var  arr        if  name   array search  var  arr true           return    name        foreach  arr as  key  gt  value          if is object  value               if  name   getReference traverse  var get object vars  value                    return    key - gt   name        Example for the above   class A       public function whatIs                 echo getReference  this             B   12   C   12   D   new A   echo getReference  B    lt br  gt       B echo getReference  C    lt br  gt       C  D- gt whatIs       D

User · Answer

Lucas on PHP net provided a reliable way to check if a variable exists  In his example  he iterates through a copy of the global variable array  or a scoped array  of variables  changes the value to a randomly generated value  and checks for the generated value in the copied array    function variable name   amp  var   scope false   prefix  UNIQUE    suffix  VARIABLE         if  scope             vals    scope        else            vals    GLOBALS             old    var       var    new    prefix rand    suffix       vname   FALSE      foreach  vals as  key   gt   val            if  val      new   vname    key             var    old      return  vname      Then try    a    asdf    b    asdf    c   FALSE   d   FALSE   echo variable name  a      a echo variable name  b      b echo variable name  c      c echo variable name  d      d   Be sure to check his post on PHP net  http   php net manual en language variables php

User · Answer

Use this to detach user variables from global to check variable at the moment     function get user var defined           return array slice  GLOBALS 8 count  GLOBALS -8           function get var name   var          vuser   get user var defined         foreach  vuser as  key  gt  value                 if  var    value  return  key

User · Answer

You could use get defined vars   to find the name of a variable that has the same value as the one you re trying to find the name of  Obviously this will not always work  since different variables often have the same values  but it s the only way I can think of to do this   Edit  get defined vars   doesn t seem to be working correctly  it returns  var  because  var is used in the function itself   GLOBALS seems to work so I ve changed it to that   function print var name  var        foreach  GLOBALS as  var name   gt   value            if   value      var                return  var name                       return false      Edit  to be clear  there is no good way to do this in PHP  which is probably because you shouldn t have to do it  There are probably better ways of doing what you re trying to do

User · Answer

You might consider changing your approach and using a variable variable name    var name    FooBar     var name    a string     then you could just   print  var name     to get   FooBar   Here s the link to the PHP manual on Variable variables

User · Answer

You could use compact   to achieve this    FooBar    a string     newArray   compact  FooBar      This would create an associative array with the variable name as the key   You could then loop through the array using the key name where you needed it   foreach  newarray as  key   gt   value        echo  key

User · Answer

Lucas on PHP net provided a reliable way to check if a variable exists  In his example  he iterates through a copy of the global variable array  or a scoped array  of variables  changes the value to a randomly generated value  and checks for the generated value in the copied array    function variable name   amp  var   scope false   prefix  UNIQUE    suffix  VARIABLE         if  scope             vals    scope        else            vals    GLOBALS             old    var       var    new    prefix rand    suffix       vname   FALSE      foreach  vals as  key   gt   val            if  val      new   vname    key             var    old      return  vname      Then try    a    asdf    b    asdf    c   FALSE   d   FALSE   echo variable name  a      a echo variable name  b      b echo variable name  c      c echo variable name  d      d   Be sure to check his post on PHP net  http   php net manual en language variables php

User · Answer

From php net   Alexandre - short solution   lt  php function vname  amp  var   scope 0         old    var      if    key   array search  var    unique  rand    value     scope    GLOBALS    scope    amp  amp   var    old  return  key        gt     Lucas - usage   lt  php   1   Use of a variable contained in the global scope  default      my global variable    My global string      echo vname  my global variable      Outputs   my global variable    2   Use of a local variable    function my local func            my local variable    My local string        return vname  my local variable  get defined vars           echo my local func       Outputs  my local variable    3   Use of an object property    class myclass         public function   constructor                this- gt my object property    My object property  string                 obj   new myclass    echo vname  obj- gt my object property   obj      Outputs  my object property   gt

User · Answer

I couldn t think of a way to do this efficiently either but I came up with this  It works  for the limited uses below    shrug   lt  php  function varName   v          trace   debug backtrace         vLine   file    FILE           fLine    vLine   trace 0   line   - 1        preg match         w       fLine   match        print r   match        foo    knight    bar   array  1  2  3     baz   12345   varName   foo    varName   bar    varName   baz       gt      Returns Array        0    gt   foo      1    gt  foo   Array        0    gt   bar      1    gt  bar   Array        0    gt   baz      1    gt  baz     It works based on the line that called the function  where it finds the argument you passed in  I suppose it could be expanded to work with multiple arguments but  like others have said  if you could explain the situation better  another solution would probably work better

User · Answer

I actually have a valid use case for this   I have a function cacheVariable  var   ok  I have a function cache  key   value   but I d like to have a function as mentioned    The purpose is to do    colour    blue   cacheVariable  colour             another session         myColour   getCachedVariable  colour      I have tried with   function cacheVariable  variable        key      variable      This doesn t help  It only gives  variable         do some caching using suitable backend such as apc  memcache or ramdisk     I have also tried with  function varName  amp  var        definedVariables   get defined vars        copyOfDefinedVariables   array       foreach   definedVariables as  variable  gt  value           copyOfDefinedVariables  variable     value           oldVar    var      var     var      difference   array diff assoc  definedVariables   copyOfDefinedVariables       var    oldVar     return key array slice  difference  0  1  true        But this fails as well        Sure  I could continue to do cache  colour    colour   but I m lazy  you know        So  what I want is a function that gets the ORIGINAL name of a variable  as it was passed to a function  Inside the function there is no way I m able to know that  as it seems  Passing get defined vars   by reference in the second example above helped me  Thanks to Jean-Jacques Guegan for that idea  somewhat  The latter function started working  but it still only kept returning the local variable   variable   not  colour      I haven t tried yet to use get func args   and get func arg       -constructs and key   combined  but I presume it will fail as well

User · Answer

If the variable is interchangable  you must have logic somewhere that s determining which variable gets used  All you need to do is put the variable name in  variable within that logic while you re doing everything else   I think we re all having a hard time understanding what you re needing this for  Sample code or an explanation of what you re actually trying to do might help  but I suspect you re way  way overthinking this

User · Answer

I couldn t think of a way to do this efficiently either but I came up with this  It works  for the limited uses below    shrug   lt  php  function varName   v          trace   debug backtrace         vLine   file    FILE           fLine    vLine   trace 0   line   - 1        preg match         w       fLine   match        print r   match        foo    knight    bar   array  1  2  3     baz   12345   varName   foo    varName   bar    varName   baz       gt      Returns Array        0    gt   foo      1    gt  foo   Array        0    gt   bar      1    gt  bar   Array        0    gt   baz      1    gt  baz     It works based on the line that called the function  where it finds the argument you passed in  I suppose it could be expanded to work with multiple arguments but  like others have said  if you could explain the situation better  another solution would probably work better

User · Answer

I think you want to know variable name with it s value  You can use an associative array to achieve this   use variable names for array keys    vars   array  FooBar    gt   a string      When you want to get variable names  use array keys  vars   it will return an array of those variable names that used in your  vars array as it s keys

User · Answer

If the variable is interchangable  you must have logic somewhere that s determining which variable gets used  All you need to do is put the variable name in  variable within that logic while you re doing everything else   I think we re all having a hard time understanding what you re needing this for  Sample code or an explanation of what you re actually trying to do might help  but I suspect you re way  way overthinking this

User · Answer

Adapted from answers above for many variables  with good performance  just one  GLOBALS scan for many  function compact assoc  amp  v1    undefined      amp  v2    undefined     amp  v3    undefined     amp  v4    undefined     amp  v5    undefined     amp  v6    undefined     amp  v7    undefined     amp  v8    undefined     amp  v9    undefined     amp  v10    undefined     amp  v11    undefined     amp  v12    undefined     amp  v13    undefined     amp  v14    undefined     amp  v15    undefined     amp  v16    undefined     amp  v17    undefined     amp  v18    undefined     amp  v19    undefined             defined vars get defined vars          result Array         reverse key Array         original value Array        foreach   defined vars as  source key   gt   source value           if  source value      undefined     break           original value  source key    source key           new test value  PREFIX  rand    SUFIX            reverse key  new test value   source key            source key  new test value             foreach  GLOBALS as  key   gt   amp  value           if  is string  value   amp  amp  isset  reverse key  value                     result  key   amp  value                      foreach   original value as  source key   gt   original value             source key  original value            return  result       a    A    b    B    c    999    myArray Array   id   gt  id123   name   gt  Foo    print r compact assoc  a  b  c  myArray        print Array        a    gt  A      b    gt  B      c    gt  999      myArray    gt  Array                        id    gt  id123              name    gt  Foo

User · Answer

This is the way I did it  function getVar  amp  var         tmp    var     store the variable value      var         amp 33xc    7 r4      give the variable a new unique value      name   array search  var   GLOBALS      search  GLOBALS for that unique value and return the key variable       var    tmp     restore the variable old value     return  name      Usage   city     San Francisco   echo getVar  city      city   Note  some PHP 7 versions will not work properly due to a bug in array search with  GLOBALS  however all other versions will work   See this https   3v4l org UMW7V

User · Answer

I know this is old and already answered but I was actually looking for this  I am posting this answer to save people a little time refining some of the answers     Option 1      data   array   FooBar        vars          vars   preg replace                data      varname   key compact  vars      echo  varname    Prints      FooBar   For whatever reason you would find yourself in a situation like this  it does actually work       Option 2      FooBar    a string       varname   trim array search  FooBar   GLOBALS      t       echo  varname    If  FooBar holds a unique value  it will print  FooBar   If  FooBar is empty or null it will print the name of the first empty or null string it finds   It could be used as such     if  isset  FooBar   amp  amp   is null  FooBar   amp  amp   empty  FooBar          FooBar    a string        varname   trim array search  FooBar   GLOBALS      t

User · Answer

I really fail to see the use case    If you will type print var name  foobar  what s so hard  and different  about typing print  foobar   instead    Because even if you were to use this in a function  you d get the local name of the variable     In any case  here s the reflection manual in case there s something you need in there

User · Answer

This is exactly what you want - its a ready to use  copy and drop in  function that echo the name of a given var   function print var name           read backtrace      bt     debug backtrace           read file      file   file  bt 0   file            select exact print var name  varname  line      src     file  bt 0   line  -1          search pattern      pat             FUNCTION                          i          extract  varname from match no 2      var    preg replace  pat    2    src          print to browser     echo trim  var       USAGE  print var name  FooBar   PRINT  FooBar     HINT   Now you can rename the function and it will still work and also use the function several times in one line  Thanks to  Cliffordlife

User · Answer

No-one seems to have mentioned the fundamental reasons why this is a  hard and b  unwise    A  variable  is just a symbol pointing at something else  In PHP  it internally points to something called a  zval   which can actually be used for multiple variables simultaneously  either because they have the same value  PHP implements something called  copy-on-write  so that  foo    bar doesn t need to allocate extra memory straight away  or because they have been assigned  or passed to a function  by reference  e g   foo   amp   bar   So a zval has no name  When you pass a parameter to a function you are creating a new variable  even if it s a reference   You could pass something anonymous  like  hello   but once inside your function  it s whatever variable you name it as  This is fairly fundamental to code separation  if a function relied on what a variable used to be called  it would be more like a goto than a properly separate function  Global variables are generally considered a bad idea  A lot of the examples here assume that the variable you want to  reflect  can be found in  GLOBALS  but this will only be true if you ve structured your code badly and variables aren t scoped to some function or object  Variable names are there to help programmers read their code  Renaming variables to better suit their purpose is a very common refactoring practice  and the whole point is that it doesn t make any difference    Now  I understand the desire for this for debugging  although some of the proposed usages go far beyond that   but as a generalised solution it s not actually as helpful as you might think  if your debug function says your variable is called   file   that could still be any one of dozens of   file  variables in your code  or a variable which you have called   filename  but are passing to a function whose parameter is called   file    A far more useful piece of information is where in your code the debug function was called from  Since you can quickly find this in your editor  you can see which variable you were outputting for yourself  and can even pass whole expressions into it in one go  e g  debug   foo    bar         foo    bar      For that  you can use this snippet at the top of your debug function    backtrace   debug backtrace    echo    Debug function called from      backtrace 0   file       at line      backtrace 0   line

User · Answer

You could use get defined vars   to find the name of a variable that has the same value as the one you re trying to find the name of  Obviously this will not always work  since different variables often have the same values  but it s the only way I can think of to do this   Edit  get defined vars   doesn t seem to be working correctly  it returns  var  because  var is used in the function itself   GLOBALS seems to work so I ve changed it to that   function print var name  var        foreach  GLOBALS as  var name   gt   value            if   value      var                return  var name                       return false      Edit  to be clear  there is no good way to do this in PHP  which is probably because you shouldn t have to do it  There are probably better ways of doing what you re trying to do

User · Answer

I really fail to see the use case    If you will type print var name  foobar  what s so hard  and different  about typing print  foobar   instead    Because even if you were to use this in a function  you d get the local name of the variable     In any case  here s the reflection manual in case there s something you need in there

User · Answer

I have this     debug echo array   query   gt  query    nrUsers   gt  nrUsers    hdr   gt  hdr      I would prefer this     debug echo  query   nrUsers   hdr     The existing function displays a yellow box with a red outline and shows each variable by name and value  The array solution works but is a little convoluted to type when it is needed   That s my use case and yes  it does have to do with debugging  I agree with those who question its use otherwise

User · Answer

It may be considered quick and dirty  but my own personal preference is to use a function method like this   public function getVarName  var             tmp   array  var   gt          keys   array keys  tmp     return trim  keys 0        basically it just creates an associative array containing one null empty element  using as a key the variable for which you want the name   we then get the value of that key using array keys and return it   obviously this gets messy quick and wouldn t be desirable in a production environment  but it works for the problem presented

User · Answer

No-one seems to have mentioned the fundamental reasons why this is a  hard and b  unwise    A  variable  is just a symbol pointing at something else  In PHP  it internally points to something called a  zval   which can actually be used for multiple variables simultaneously  either because they have the same value  PHP implements something called  copy-on-write  so that  foo    bar doesn t need to allocate extra memory straight away  or because they have been assigned  or passed to a function  by reference  e g   foo   amp   bar   So a zval has no name  When you pass a parameter to a function you are creating a new variable  even if it s a reference   You could pass something anonymous  like  hello   but once inside your function  it s whatever variable you name it as  This is fairly fundamental to code separation  if a function relied on what a variable used to be called  it would be more like a goto than a properly separate function  Global variables are generally considered a bad idea  A lot of the examples here assume that the variable you want to  reflect  can be found in  GLOBALS  but this will only be true if you ve structured your code badly and variables aren t scoped to some function or object  Variable names are there to help programmers read their code  Renaming variables to better suit their purpose is a very common refactoring practice  and the whole point is that it doesn t make any difference    Now  I understand the desire for this for debugging  although some of the proposed usages go far beyond that   but as a generalised solution it s not actually as helpful as you might think  if your debug function says your variable is called   file   that could still be any one of dozens of   file  variables in your code  or a variable which you have called   filename  but are passing to a function whose parameter is called   file    A far more useful piece of information is where in your code the debug function was called from  Since you can quickly find this in your editor  you can see which variable you were outputting for yourself  and can even pass whole expressions into it in one go  e g  debug   foo    bar         foo    bar      For that  you can use this snippet at the top of your debug function    backtrace   debug backtrace    echo    Debug function called from      backtrace 0   file       at line      backtrace 0   line

User · Answer

Here s my solution based on Jeremy Ruten  class DebugHelper        function printVarNames  systemDefinedVars   varNames            foreach   systemDefinedVars as  var  gt  value                if  in array  var   varNames                      var dump  var                   var dump  value                                     using it  DebugHelper  printVarNames       systemDefinedVars   get defined vars         varNames array  yourVar00    yourVar01

User · Answer

I know this is old and already answered but I was actually looking for this  I am posting this answer to save people a little time refining some of the answers     Option 1      data   array   FooBar        vars          vars   preg replace                data      varname   key compact  vars      echo  varname    Prints      FooBar   For whatever reason you would find yourself in a situation like this  it does actually work       Option 2      FooBar    a string       varname   trim array search  FooBar   GLOBALS      t       echo  varname    If  FooBar holds a unique value  it will print  FooBar   If  FooBar is empty or null it will print the name of the first empty or null string it finds   It could be used as such     if  isset  FooBar   amp  amp   is null  FooBar   amp  amp   empty  FooBar          FooBar    a string        varname   trim array search  FooBar   GLOBALS      t

User · Answer

There is no predefined function in PHP that can output the name of a variable  However  you can use the result of get defined vars    which returns all the variables defined in the scope  including name and value  Here is an example   lt  php        Function for determining the name of a variable     function getVarName  amp  var   definedVars null             definedVars     is array  definedVars     GLOBALS    definedVars            val    var           rand   1          while  in array  rand   definedVars  true                  rand   md5 mt rand 10000  1000000                       var    rand                    foreach   definedVars as  dvName  gt  dvVal                if   dvVal      rand                     var    val                  return  dvName                                            return null                 the name of  a is to be determined          a   1               Determine the name of  a     echo getVarName  a     gt   Read more in How to get a variable name as a string in PHP

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From php net   Alexandre - short solution   lt  php function vname  amp  var   scope 0         old    var      if    key   array search  var    unique  rand    value     scope    GLOBALS    scope    amp  amp   var    old  return  key        gt     Lucas - usage   lt  php   1   Use of a variable contained in the global scope  default      my global variable    My global string      echo vname  my global variable      Outputs   my global variable    2   Use of a local variable    function my local func            my local variable    My local string        return vname  my local variable  get defined vars           echo my local func       Outputs  my local variable    3   Use of an object property    class myclass         public function   constructor                this- gt my object property    My object property  string                 obj   new myclass    echo vname  obj- gt my object property   obj      Outputs  my object property   gt

User · Answer

why we have to use globals to get variable name    we can use simply like below        variableName    ajaxmint        echo getVarName   variableName         function getVarName  name            return str replace         name

User · Answer

why we have to use globals to get variable name    we can use simply like below        variableName    ajaxmint        echo getVarName   variableName         function getVarName  name            return str replace         name

User · Answer

Here s my solution based on Jeremy Ruten  class DebugHelper        function printVarNames  systemDefinedVars   varNames            foreach   systemDefinedVars as  var  gt  value                if  in array  var   varNames                      var dump  var                   var dump  value                                     using it  DebugHelper  printVarNames       systemDefinedVars   get defined vars         varNames array  yourVar00    yourVar01

User · Answer

I couldn t think of a way to do this efficiently either but I came up with this  It works  for the limited uses below    shrug   lt  php  function varName   v          trace   debug backtrace         vLine   file    FILE           fLine    vLine   trace 0   line   - 1        preg match         w       fLine   match        print r   match        foo    knight    bar   array  1  2  3     baz   12345   varName   foo    varName   bar    varName   baz       gt      Returns Array        0    gt   foo      1    gt  foo   Array        0    gt   bar      1    gt  bar   Array        0    gt   baz      1    gt  baz     It works based on the line that called the function  where it finds the argument you passed in  I suppose it could be expanded to work with multiple arguments but  like others have said  if you could explain the situation better  another solution would probably work better

User · Answer

You might consider changing your approach and using a variable variable name    var name    FooBar     var name    a string     then you could just   print  var name     to get   FooBar   Here s the link to the PHP manual on Variable variables

User · Answer

I actually have a valid use case for this   I have a function cacheVariable  var   ok  I have a function cache  key   value   but I d like to have a function as mentioned    The purpose is to do    colour    blue   cacheVariable  colour             another session         myColour   getCachedVariable  colour      I have tried with   function cacheVariable  variable        key      variable      This doesn t help  It only gives  variable         do some caching using suitable backend such as apc  memcache or ramdisk     I have also tried with  function varName  amp  var        definedVariables   get defined vars        copyOfDefinedVariables   array       foreach   definedVariables as  variable  gt  value           copyOfDefinedVariables  variable     value           oldVar    var      var     var      difference   array diff assoc  definedVariables   copyOfDefinedVariables       var    oldVar     return key array slice  difference  0  1  true        But this fails as well        Sure  I could continue to do cache  colour    colour   but I m lazy  you know        So  what I want is a function that gets the ORIGINAL name of a variable  as it was passed to a function  Inside the function there is no way I m able to know that  as it seems  Passing get defined vars   by reference in the second example above helped me  Thanks to Jean-Jacques Guegan for that idea  somewhat  The latter function started working  but it still only kept returning the local variable   variable   not  colour      I haven t tried yet to use get func args   and get func arg       -constructs and key   combined  but I presume it will fail as well

User · Answer

I was looking for this but just decided to pass the name in  I usually have the name in the clipboard anyway   function VarTest  my var  my var name       echo      my var name       my var   lt br   gt        fruit  apple   VarTest  fruit  fruit

User · Answer

I couldn t think of a way to do this efficiently either but I came up with this  It works  for the limited uses below    shrug   lt  php  function varName   v          trace   debug backtrace         vLine   file    FILE           fLine    vLine   trace 0   line   - 1        preg match         w       fLine   match        print r   match        foo    knight    bar   array  1  2  3     baz   12345   varName   foo    varName   bar    varName   baz       gt      Returns Array        0    gt   foo      1    gt  foo   Array        0    gt   bar      1    gt  bar   Array        0    gt   baz      1    gt  baz     It works based on the line that called the function  where it finds the argument you passed in  I suppose it could be expanded to work with multiple arguments but  like others have said  if you could explain the situation better  another solution would probably work better

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Why don t you just build a simple function and TELL it          Prints out  obj for debug        param any type  obj     param  string   title     function print all   obj   title   false         print   n lt div style   font-family Arial    gt  n       if   title   print   lt div style   background-color red  color white  font-size 16px  font-weight bold  margin 0  padding 10px  text-align center    gt  title lt  div gt  n       print   lt pre style   background-color yellow  border 2px solid red  color black  margin 0  padding 10px    gt  n n       var export   obj        print   n n lt  pre gt  n lt  div gt  n      print all   aUser    aUser

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Why don t you just build a simple function and TELL it          Prints out  obj for debug        param any type  obj     param  string   title     function print all   obj   title   false         print   n lt div style   font-family Arial    gt  n       if   title   print   lt div style   background-color red  color white  font-size 16px  font-weight bold  margin 0  padding 10px  text-align center    gt  title lt  div gt  n       print   lt pre style   background-color yellow  border 2px solid red  color black  margin 0  padding 10px    gt  n n       var export   obj        print   n n lt  pre gt  n lt  div gt  n      print all   aUser    aUser

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I made an inspection function for debugging reasons   It s like print r   on steroids  much like Krumo but a little more effective on objects   I wanted to add the var name detection and came out with this  inspired by Nick Presta s post on this page   It detects any expression passed as an argument  not only variable names     This is only the wrapper function that detects the passed expression  Works on most of the cases   It will not work if you call the function more than once in the same line of code   This works fine   die inspect  this- getUser  - hasCredential  delete       inspect   is the function that will detect the passed expression   We get        this- getUser  - hasCredential  delete    function inspect  label   value      undefin e d           if  value       undefin e d                   The first argument is not the label but the             variable to inspect itself  so we need a label             Let s try to find out it s name by peeking at             the source code                          The reason for using an exotic string like                undefin e d    instead of NULL here is that             inspected variables can also be NULL and I want             to inspect them anyway                       value    label            bt   debug backtrace             src   file  bt 0   file              line    src   bt 0   line   - 1                let s match the function call and the last closing bracket         preg match    inspect             line   match                let s count brackets to see how many of them actually belongs             to the var name            Eg    die inspect  this- gt getUser  - gt hasCredential  delete                        We want     this- gt getUser  - gt hasCredential  delete                       max   strlen  match 1             varname                c   0          for  i   0   i  lt   max   i                 if       match 1   i            c                elseif   match 1   i            c--              if  c  lt  0  break               varname      match 1   i                      label    varname                 label now holds the name of the passed variable    included         Eg    inspect  hello                        gt   label     hello         or the whole expression evaluated        Eg    inspect  this- gt getUser  - gt hasCredential  delete                         gt   label     this- gt getUser  - gt hasCredential   delete             now the actual function call to the inspector method          passing the var name as the label            return dInspect  dump  label   val               UPDATE  I commented this line because people got confused about              the dInspect class  wich has nothing to do with the issue here       echo  The label is     label       echo  The value is     value        Here s an example of the inspector function  and my dInspect class  in action   http   inspect ip1 cc  Texts are in spanish in that page  but code is concise and really easy to understand

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It may be considered quick and dirty  but my own personal preference is to use a function method like this   public function getVarName  var             tmp   array  var   gt          keys   array keys  tmp     return trim  keys 0        basically it just creates an associative array containing one null empty element  using as a key the variable for which you want the name   we then get the value of that key using array keys and return it   obviously this gets messy quick and wouldn t be desirable in a production environment  but it works for the problem presented

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You could use get defined vars   to find the name of a variable that has the same value as the one you re trying to find the name of  Obviously this will not always work  since different variables often have the same values  but it s the only way I can think of to do this   Edit  get defined vars   doesn t seem to be working correctly  it returns  var  because  var is used in the function itself   GLOBALS seems to work so I ve changed it to that   function print var name  var        foreach  GLOBALS as  var name   gt   value            if   value      var                return  var name                       return false      Edit  to be clear  there is no good way to do this in PHP  which is probably because you shouldn t have to do it  There are probably better ways of doing what you re trying to do

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You could use get defined vars   to find the name of a variable that has the same value as the one you re trying to find the name of  Obviously this will not always work  since different variables often have the same values  but it s the only way I can think of to do this   Edit  get defined vars   doesn t seem to be working correctly  it returns  var  because  var is used in the function itself   GLOBALS seems to work so I ve changed it to that   function print var name  var        foreach  GLOBALS as  var name   gt   value            if   value      var                return  var name                       return false      Edit  to be clear  there is no good way to do this in PHP  which is probably because you shouldn t have to do it  There are probably better ways of doing what you re trying to do

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This is exactly what you want - its a ready to use  copy and drop in  function that echo the name of a given var   function print var name           read backtrace      bt     debug backtrace           read file      file   file  bt 0   file            select exact print var name  varname  line      src     file  bt 0   line  -1          search pattern      pat             FUNCTION                          i          extract  varname from match no 2      var    preg replace  pat    2    src          print to browser     echo trim  var       USAGE  print var name  FooBar   PRINT  FooBar     HINT   Now you can rename the function and it will still work and also use the function several times in one line  Thanks to  Cliffordlife

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You might consider changing your approach and using a variable variable name    var name    FooBar     var name    a string     then you could just   print  var name     to get   FooBar   Here s the link to the PHP manual on Variable variables

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I think you want to know variable name with it s value  You can use an associative array to achieve this   use variable names for array keys    vars   array  FooBar    gt   a string      When you want to get variable names  use array keys  vars   it will return an array of those variable names that used in your  vars array as it s keys

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I have this     debug echo array   query   gt  query    nrUsers   gt  nrUsers    hdr   gt  hdr      I would prefer this     debug echo  query   nrUsers   hdr     The existing function displays a yellow box with a red outline and shows each variable by name and value  The array solution works but is a little convoluted to type when it is needed   That s my use case and yes  it does have to do with debugging  I agree with those who question its use otherwise

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I made an inspection function for debugging reasons   It s like print r   on steroids  much like Krumo but a little more effective on objects   I wanted to add the var name detection and came out with this  inspired by Nick Presta s post on this page   It detects any expression passed as an argument  not only variable names     This is only the wrapper function that detects the passed expression  Works on most of the cases   It will not work if you call the function more than once in the same line of code   This works fine   die inspect  this- getUser  - hasCredential  delete       inspect   is the function that will detect the passed expression   We get        this- getUser  - hasCredential  delete    function inspect  label   value      undefin e d           if  value       undefin e d                   The first argument is not the label but the             variable to inspect itself  so we need a label             Let s try to find out it s name by peeking at             the source code                          The reason for using an exotic string like                undefin e d    instead of NULL here is that             inspected variables can also be NULL and I want             to inspect them anyway                       value    label            bt   debug backtrace             src   file  bt 0   file              line    src   bt 0   line   - 1                let s match the function call and the last closing bracket         preg match    inspect             line   match                let s count brackets to see how many of them actually belongs             to the var name            Eg    die inspect  this- gt getUser  - gt hasCredential  delete                        We want     this- gt getUser  - gt hasCredential  delete                       max   strlen  match 1             varname                c   0          for  i   0   i  lt   max   i                 if       match 1   i            c                elseif   match 1   i            c--              if  c  lt  0  break               varname      match 1   i                      label    varname                 label now holds the name of the passed variable    included         Eg    inspect  hello                        gt   label     hello         or the whole expression evaluated        Eg    inspect  this- gt getUser  - gt hasCredential  delete                         gt   label     this- gt getUser  - gt hasCredential   delete             now the actual function call to the inspector method          passing the var name as the label            return dInspect  dump  label   val               UPDATE  I commented this line because people got confused about              the dInspect class  wich has nothing to do with the issue here       echo  The label is     label       echo  The value is     value        Here s an example of the inspector function  and my dInspect class  in action   http   inspect ip1 cc  Texts are in spanish in that page  but code is concise and really easy to understand

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Many replies question the usefulness of this  However  getting a reference for a variable can be very useful  Especially in cases with objects and  this  My solution works with objects  and as property defined objects as well   function getReference  amp  var        if is object  var            var- gt    uniqid   uniqid        else          var   serialize  var        name   getReference traverse  var  GLOBALS       if is object  var           unset  var- gt    uniqid       else          var   unserialize  var       return      name           function getReference traverse  amp  var  arr        if  name   array search  var  arr true           return    name        foreach  arr as  key  gt  value          if is object  value               if  name   getReference traverse  var get object vars  value                    return    key - gt   name        Example for the above   class A       public function whatIs                 echo getReference  this             B   12   C   12   D   new A   echo getReference  B    lt br  gt       B echo getReference  C    lt br  gt       C  D- gt whatIs       D

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If the variable is interchangable  you must have logic somewhere that s determining which variable gets used  All you need to do is put the variable name in  variable within that logic while you re doing everything else   I think we re all having a hard time understanding what you re needing this for  Sample code or an explanation of what you re actually trying to do might help  but I suspect you re way  way overthinking this

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This is the way I did it  function getVar  amp  var         tmp    var     store the variable value      var         amp 33xc    7 r4      give the variable a new unique value      name   array search  var   GLOBALS      search  GLOBALS for that unique value and return the key variable       var    tmp     restore the variable old value     return  name      Usage   city     San Francisco   echo getVar  city      city   Note  some PHP 7 versions will not work properly due to a bug in array search with  GLOBALS  however all other versions will work   See this https   3v4l org UMW7V

[php] How to get a variable name as a string in PHP?

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