PHP Variable

• Variable is name to the memory location.its a one kind of container which hold any type of data to perform operation on it. php variables doesn't need to specify which type of variable we would like to declare.

• Variables are used for storing values, such as numbers, strings or function results, so that they can be used many times in a script.
• When a variable is set it can be used over and over again in your script.
• All variables in PHP start with a $ sign symbol.
• Example : $var_name = value;New PHP programmers often forget the $ sign at thebeginning of the variable. In that case it will not work.
• PHP is a Loosely Typed Language so, In PHP a variable does not need to be declared before being set.
• PHP automatically converts the variable to the correct data type, depending on how they are set.
• In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
• In PHP the variable is declared automatically when you use it.
• Example : $value=25 

Rules for Constructing PHP variable:

• Must always begin with a dollar-sign ($).
• Generally start with a letter and can contain letters, numbers, and underscore characters “_”.
• Values can be numbers, strings, boolean, etc....
• Names are case sensitive.
• value gets change as the program executes.

PHP supports eight primitive data types :

Four scalar types:

• Boolean
• Integer
• Float
• String

Two compound types:

• Array
• Object

Two special types:

• Resource
• Null