What does the variable this mean in PHP

Question

I see the variable  this in PHP all the time and I have no idea what it s used for  I ve never personally used it    Can someone tell me how the variable  this works in PHP

User · Answer

I know its old question  anyway another exact explanation about  this   this is mainly used to refer properties of a class   Example   Class A      public  myname       this is a member variable of this class  function callme          myname    function variable        this- gt myname    Member variable       echo  myname                     prints function variable     echo  this- gt myname                 prints member variable          output   function variable  member variable

User · Answer

this is a special variable and it refers to the same object ie  itself   it actually refer instance of current class  here is an example which will clear the above statement   lt  php  class Books        Member variables      var  price    var  title        Member functions      function setPrice  par         this- gt price    par         function getPrice         echo  this- gt price    lt br  gt           function setTitle  par         this- gt title    par         function getTitle         echo  this- gt title     lt br  gt            gt

User · Answer

It s a reference to the current object  it s most commonly used in object oriented code    Reference  http   www php net manual en language oop5 basic php Primer  http   www phpro org tutorials Object-Oriented-Programming-with-PHP html   Example    lt  php class Person       public  name       function   construct   name              this- gt name    name             jack   new Person  Jack    echo  jack- gt name    This stores the  Jack  string as a property of the object created

User · Answer

Generally  this keyword is used inside a class  generally with in the member functions to access non-static members of a class variables or functions  for the current object   this keyword should be preceded with a   symbol  In case of this operator  we use the - gt  symbol  Whereas   this will refer the member variables and function for a particular instance   Let s take an example to understand the usage of  this   lt  php class Hero          first name of hero     private  name              public function to set value for name  setter method      public function setName  name             this- gt name    name                    public function to get value of name  getter method      public function getName             return  this- gt name              creating class object  stark   new Hero        calling the public function to set fname  stark- gt setName  quot IRON MAN quot        getting the value of the name variable echo  quot I Am  quot     stark- gt getName      gt    OUTPUT  I am IRON MAN  NOTE  A static variable acts as a global variable and is shared among all the objects of the class  A non-static variables are specific to instance object in which they are created

User · Answer

Lets see what happens if we won t use  this and try to have instance variables and  constructor arguments with the same name with the following code snippet   lt  php  class Student       public  name       function   construct   name              name    name             tom   new Student  Tom    echo  tom- gt name     gt    It echos nothing but    lt  php  class Student       public  name       function   construct   name              this- gt name    name     Using  this  to access the student s name            tom   new Student  Tom    echo  tom- gt name     gt    this echoes  Tom

User · Answer

It is the way to reference an instance of a class from within itself  the same as many other object oriented languages   From the PHP docs      The pseudo-variable  this is available   when a method is called from within an   object context   this is a reference   to the calling object  usually the   object to which the method belongs    but possibly another object  if the   method is called statically from the   context of a secondary object

User · Answer

this is a reference to the calling object  usually the object to which the method belongs  but possibly another object  if the method is called statically from the context of a secondary object

User · Answer

The best way to learn about the  this variable in PHP is to try it against the interpreter in various contexts   print isset  this                  true     this exists print gettype  this                Object   this is an object  print is array  this               false    this isn t an array print get object vars  this        true     this s variables are an array print is object  this              true     this is still an object print get class  this              YourProject YourFile YourClass print get parent class  this       YourBundle YourStuff YourParentClass print gettype  this- gt container     object print r  this                      delicious data dump of  this print  this- gt yourvariable          access  this variable with - gt    So the  this pseudo-variable has the Current Object s method s and properties   Such a thing is useful because it lets you access all member variables and member methods inside the class   For example   Class Dog      public  my member variable                                member variable      function normal method inside Dog                         member method            Assign data to member variable from inside the member method          this- gt my member variable    whatever              Get data from member variable from inside the member method          print  this- gt my member variable             this is reference to a PHP Object that was created by the interpreter for you  that contains an array of variables   If you call  this inside a normal method in a normal class   this returns the Object  the class  to which that method belongs     It s possible for  this to be undefined if the context has no parent Object     php net has a big page talking about PHP object oriented programming and how  this behaves depending on context    https   www php net manual en language oop5 basic php

User · Answer

when you create a class you have  in many cases  instance variables and methods  aka  functions     this accesses those instance variables so that your functions can take those variables and do what they need to do whatever you want with them   another version of meder s example   class Person        protected  name     can t be accessed from outside the class      public function   construct  name             this- gt name    name             public function getName             return  this- gt name             this line creates an instance of the class Person setting  Jack  as  name         construct   gets executed when you declare it within the class   jack   new Person  Jack      echo  jack- gt getName     Output   Jack

User · Answer

This is long detailed explanation  I hope this will help the beginners  I will make it very simple  First  let s create a class  lt  php   class Class1           You can omit the php closing tag   gt  if you are using php code only  Now let s add properties and a method inside Class1   lt  php   class Class1       public  property1    quot I am property 1 quot       public  property2    quot I am property 2 quot        public function Method1                 return  quot I am Method 1 quot            The property is just a simple variable   but we give it the name property cuz its inside a class  The method is just a simple function   but we say method cuz its also inside a class  The public keyword mean that the method or a property can be accessed anywhere in the script  Now  how we can use the properties and the method inside Class1   The answer is creating an instance or an object  think of an object as a copy of the class   lt  php   class Class1       public  property1    quot I am property 1 quot       public  property2    quot I am property 2 quot        public function Method1                 return  quot I am Method 1 quot             object1   new Class1  var dump  object1    We created an object  which is  object1   which is a copy of Class1 with all its contents  And we dumped all the contents of  object1 using var dump     This will give you object Class1  1  2      quot property1 quot    gt  string 15   quot I am property 1 quot    quot property2 quot    gt  string 15   quot I am property 2 quot     So all the contents of Class1 are in  object1   except Method1   i don t know why methods doesn t show while dumping objects  Now what if we want to access  property1 only  Its simple   we do var dump  object1- gt property1     we just added - gt property1   we pointed to it  we can also access Method1     we do var dump  object1- gt Method1      Now suppose i want to access  property1 from inside Method1     i will do this  lt  php   class Class1       public  property1    quot I am property 1 quot       public  property2    quot I am property 2 quot        public function Method1                     object2   new Class1          return  object2- gt property1            object1   new Class1  var dump  object1- gt Method1       we created  object2   new Class1  which is a new copy of Class1 or we can say an instance  Then we pointed to property1 from  object2 return  object2- gt property1   This will print string 15   quot I am property 1 quot  in the browser  Now instead of doing this inside Method1    object2   new Class1  return  object2- gt property1   We do this return  this- gt property1   The  this object is used inside the class to refer to the class itself  It is an alternative for creating new object and then returning it like this  object2   new Class1  return  object2- gt property1   Another example  lt  php   class Class1       public  property1   119      public  property2   666      public  result       public function Method1                     this- gt result    this- gt property1    this- gt property2          return  this- gt result            object1   new Class1  var dump  object1- gt Method1      We created 2 properties containing integers and then we added them and put the result in  this- gt result  Do not forget that  this- gt property1    property1   119 they have that same value    etc I hope that explains the idea  This series of videos will help you a lot in OOP https   www youtube com playlist list PLe30vg FG4OSEHH6bRF8FrA7wmoAMUZLv

User · Answer

It refers to the instance of the current class  as meder said   See the PHP Docs  It s explained under the first example

[php] What does the variable $this mean in PHP?

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