PHP Data Types

• Data types of PHP.
• PHP provides for six data types. Each data type is used to store a different type of data.
• An integer is  a whole number that can start with positive or nagative sign.
• A double value consists of a positive and nagative sign,digits, an optional decimal point, and optional decimal digist.
• A boolean data type is used to represent a boolean value that is either True or False.
• A string data type contains string that are made up of any characters.
• An array data type is used to store one or more items called elements.Each element stores a value that you can refer to with an index.
• An object data type.

• Declaring variables in PHP.
• Variable stores a value that can change as the program executes. In php, variables are easy to spot beacause they all begin with dollar sign ($).
• To declare a variable, code the dollar sign ($) followed by the variable name. Then, to assign a value to  the variable, code assignment operator (=) followed by an expression that return value for the variable.
• Example: $count=10; or name='nguyen tien dung'.

• Declaring constants in PHP.
• Constants like variable except that once they are declared they can't change or undefined.
• Example:  define('pi',3,14).