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PHP $ and $$ - javatpoint

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PHP $ and $$ Variables

The $var (single dollar) is a normal variable with the name var that stores any value like string, integer, float, etc.

The $$var (double dollar) is a reference variable that stores the value of the $variable inside it.

 

To understand the difference better, let's see some examples.

Example 1

  1. <?php  
  2. $x = "abc";  
  3. $$x = 200;  
  4. echo $x."<br/>";  
  5. echo $$x."<br/>";  
  6. echo $abc;  
  7. ?>  

Output:

 

 

In the above example, we have assigned a value to the variable x as abc. Value of reference variable $$x is assigned as 200.

Now we have printed the values $x, $$x and $abc.

Example2

  1. <?php  
  2.  $x="U.P";  
  3. $$x="Lucknow";  
  4. echo $x. "<br>";  
  5. echo $$x. "<br>";  
  6. echo "Capital of $x is " . $$x;  
  7. ?>  

Output:

In the above example, we have assigned a value to the variable x as U.P. Value of reference variable $$x is assigned as Lucknow.

Now we have printed the values $x, $$x and a string.

Example3

  1. <?php  
  2. $name="Cat";  
  3. ${$name}="Dog";  
  4. ${${$name}}="Monkey";  
  5. echo $name. "<br>";  
  6. echo ${$name}. "<br>";  
  7. echo $Cat. "<br>";  
  8. echo ${${$name}}. "<br>";  
  9. echo $Dog. "<br>";  
  10. ?>  

Output:

In the above example, we have assigned a value to the variable name Cat. Value of reference variable ${$name} is assigned as Dog and ${${$name}} as Monkey.

Now we have printed the values as $name, ${$name}, $Cat, ${${$name}} and $Dog.

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