What is function overloading and overriding in php

Question

In PHP  what do you mean by function overloading and function overriding  and what is the difference between both of them  couldn t figure out what is the difference between them

User · Answer

PHP 5 x x does not support overloading this is why PHP is not fully OOP

User · Answer

Function overloading occurs when you define the same function name twice  or more  using different set of parameters  For example   class Addition     function compute  first   second        return  first  second         function compute  first   second   third        return  first  second  third          In the example above  the function compute is overloaded with two different parameter signatures   This is not yet supported in PHP  An alternative is to use optional arguments   class Addition     function compute  first   second   third   0        return  first  second  third            Function overriding occurs when you extend a class and rewrite a function which existed in the parent class   class Substraction extends Addition     function compute  first   second   third   0        return  first- second- third          For example  compute overrides the behavior set forth in Addition

User · Answer

Method overloading occurs when two or more methods with same method name but different number of parameters in single class  PHP does not support method overloading  Method overriding means two methods with same method name and same number of parameters in two different classes means parent class and child class

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I would like to point out over here that Overloading in PHP has a completely different meaning as compared to other programming languages  A lot of people have said that overloading isnt supported in PHP and by the conventional definition of overloading  yes that functionality isnt explicitly available    However  the correct definition of overloading in PHP is completely different    In PHP overloading refers to dynamically creating properties and methods using magic methods like   set   and   get    These overloading methods are invoked when interacting with methods or properties that are not accessible or not declared    Here is a link from the PHP manual   http   www php net manual en language oop5 overloading php

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Overloading Example  class overload       public  name      public function   construct  agr             this- gt name    agr            public function   call  methodname   agrument             if  methodname     sum2                if count  agrument     2                   this- gt sum  agrument 0    agrument 1                          if count  agrument     3                   echo  this- gt sum1  agrument 0    agrument 1    agrument 2                                    public function sum  a   b            return  a    b            public function sum1  a  b  c             return  a    b    c           object   new overload  Sum    echo  object- gt sum2 1 2 3

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There are some differences between Function overloading  amp  overriding though both contains the same function name In overloading  between the same name functions  contain different type of argument or return type Such as     function add  int a int b    amp   function add float a float b   Here the add   function is overloaded  In the case of overriding both the argument and function name are same It generally found in inheritance or in traits We have to follow some tactics to introduce  what function will execute now   So In overriding the programmer follows some tactics to execute the desired function where in the overloading the program can automatically identify the desired function   Thanks

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Overloading is defining functions that have similar signatures  yet have different parameters  Overriding is only pertinent to derived classes  where the parent class has defined a method and the derived class wishes to override that method   In PHP  you can only overload methods using the magic method   call   An example of overriding    lt  php  class Foo      function myFoo           return  Foo           class Bar extends Foo      function myFoo           return  Bar            foo   new Foo   bar   new Bar  echo  foo- gt myFoo        Foo  echo  bar- gt myFoo        Bar    gt

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Overloading  In Real world  overloading means assigning some extra stuff to someone  As as in real world Overloading in PHP means calling extra functions  In other way You can say it have slimier function with different parameter In PHP you can use overloading with magic functions e g    get    set    call etc   Example of Overloading    class Shape      const Pi   3 142       constant value   function   call  functionname   argument       if  functionname     area       switch count  argument            case 0   return 0           case 1   return self  Pi    argument 0       3 14   5         case 2   return  argument 0     argument 1       5   10                  circle   new Shape    enter code here   echo  Area of circle    circle- gt area     lt  br gt       display the area of circle Output 0  echo  Area of circle    circle- gt area 5    lt  br gt       display the area of circle   rect   new Shape     echo  Area of rectangle    rect- gt area 5 10      display area of rectangle   Overriding   In object oriented programming overriding is to replace parent method in child class In overriding you can re-declare parent class method in child class  So  basically the purpose of overriding is to change the behavior of your parent class method   Example of overriding    class parent class      public function text        text   is a parent class method         echo  Hello   everyone I am parent class text method    lt  br gt          public function test              echo  Hello   I am second method of parent class    lt  br gt            class child extends parent class     public function text          Text   parent class method which is override by child    class         echo  Hello   Everyone i am child class              obj  new parent class      obj- gt text                  display the parent class method echo   obj  new parent class      obj- gt test      obj  new child      obj- gt text       display the child class method echo

User · Answer

Although overloading paradigm is not fully supported by PHP the same  or very similar  effect can be achieved with default parameter s   as somebody mentioned before    If you define your function like this   function f  p 0      if  p            implement functionality  1 here       else           implement functionality  2 here         When you call this function like   f      you ll get one functionality   1   but if you call it with parameter like   f 1     you ll get another functionality   2   That s the effect of overloading - different functionality depending on function s input parameter s    I know  somebody will ask now what functionality one will get if he she calls this function as f 0

User · Answer

Strictly speaking  there s no difference  since you cannot do either     Function overriding could have been done with a PHP extension like APD  but it s deprecated and afaik last version was unusable   Function overloading in PHP cannot be done due to dynamic typing  ie  in PHP you don t  define  variables to be a particular type  Example    a 1   a  1    a true   a doSomething      Each variable is of a different type  yet you can know the type before execution  see the 4th one   As a comparison  other languages use   int a 1  String s  1   bool a true  something a doSomething      In the last example  you must forcefully set the variable s type  as an example  I used data type  something       Another  issue  why function overloading is not possible in PHP  PHP has a function called func get args    which returns an array of current arguments  now consider the following code   function hello  a     print r func get args        function hello  a  a     print r func get args        hello  a    hello  a   b      Considering both functions accept any amount of arguments  which one should the compiler choose     Finally  I d like to point out why the above replies are partially wrong  function overloading overriding is NOT equal to method overloading overriding   Where a method is like a function but specific to a class  in which case  PHP does allow overriding in classes  but again no overloading  due to language semantics   To conclude  languages like Javascript allow overriding  but again  no overloading   however they may also show the difference between overriding a user function and a method       Function Overriding      function a       alert  a      a function       alert  b       a       shows popup with  b        Method Overriding      var a      a  function        alert  a          a a function       alert  b       a a       shows popup with  b

[php] What is function overloading and overriding in php?

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