PHP Variables

Variables are used to store data which are further used and manipulated as per requirement or instructions. In PHP,  a variable name is declared with a ‘$’ symbol and is followed by the variable name. It can be assigned a value using Assignment Operator (=). Syntax of declaring and defining PHP variable is:

<?php
	$variableName = value;
?>

However, there are some rules to follow while declaring a variable name in PHP which are mentioned below:

  • As discussed earlier, a variable name must start with a ‘$’ symbol, followed by the name of its variable.
  • Variable names are case sensitive. i.e.- $var is different from $VAR;
  • A variable name must start with a letter or an underscore (_) followed by letters, numbers or underscores.
  • A variable name cannot contain whitespace.

VARIABLE DECLARATION IN PHP

<?php
	$name = "Sehaj Kaur";		// String variable
	$age = 12;			// Integer variable
	$english_marks = 99.5;		// float variable
	$science_marks = 90.2;
	$total = $english_marks + $science_marks;      // performing arithmetic operation
	echo "Name  -> ".$name;				// displaying values on screen
	echo "<br>Age -> ".$age;
	echo "<br>Total Marks -> ".$total; 
?>

OUTPUT

Name -> Sehaj Kaur

Age -> 12

Total Marks -> 189.7

Assign By Reference :

In PHP, we can also assign values to the variables by reference. The newly created variable becomes an alias for the original variable. If we change the value of a new variable it will affect the value of the original variable as well and vice-versa. The syntax looks like:                                 

EXAMPLE :
<?php
			$originalVar = “Programming”;	// source variable           
			$alias = &$originalVar;	// value assigned by reference
			$alias = “Computer Programming”;   // Altering the value of alias variable
			echo $originalVar;
			echo “<br>”.$alias;
		?>

                                    OUTPUT

                                    Computer Programming

                                    Computer Programming

Note* : In PHP, if variables are not initialized they are supposed to have default values of the context in which they are used. For example : Integers and floats are set to zero by default, arrays and strings are empty if not initialized and a boolean is set to false.