PHP Basic Tutorial-data types

PHP supports eight primitive types (type).

Four types of scalar:

String (String)

Integer (integer type)

Float (floating point type, also double)

Boolean (Boolean)

Two kinds of composite types:

Array (arrays)

Object (Objects)

Two special types:

Resource (resources)

Null (empty)

How to view variable types

The GetType () function makes it easy to see the type of a variable:

<?php$var_bool = TRUE; A boolean$var_str = "foo"; a string$var_int = 12; An Integerecho GetType ($var _bool); Output Booleanecho GetType ($var _str); Output Stringecho GetType ($var _int); Output integer?>

Tips

For historical reasons, if the data is float type, the GetType () function returns a double instead of float.

If you want to see the value and type of an expression, use the Var_dump () function.

If you want to cast a variable to a type, you can use a cast or settype () function on it.

PHP string

The string is a sequence of characters, such as "Hello world!".

The string can be any text within quotation marks. You can use single or double quotation marks:

Instance

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<?php $x= "Hello anxia.com!";echo $x;echo "<br>"; $x = ‘Hello anxia.com!‘;echo$x;?>

PHP integer

Integers are numbers that have no decimals.

Integer rule:

• Integers must have at least one number (0-9)

• Integers cannot contain commas or spaces

• Integers cannot have decimal points

• Integers can be both positive and negative

• Integers can be specified in three formats: decimal, hexadecimal (prefix 0x), or octal (prefix 0)

In the example below, we will test for different numbers. PHP Var_dump () returns the data type and value of the variable:

Instance

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<?php $x= 5985;var_dump($x);echo"<br>"; $x = -345; // 负数var_dump($x);echo"<br>"; $x= 0x8C; // 十六进制数var_dump($x);echo"<br>";$x= 047; // 八进制数var_dump($x);?>

PHP floating-point number

Floating-point numbers are digits that have decimal or exponential form.

In the example below, we will test for different numbers. PHP Var_dump () returns the data type and value of the variable:

Instance

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<?php  $x  = 10.365; var_dump ( $x echo   "<br>" ;&NBSP; $x  =&NBSP;2.4E3; var_dump ( $x echo   "<br>" ;&NBSP; $x  = 8e-5; var_dump ( $x ?>

PHP Logic/Boolean type

The logic is true or false.

12	$x=true;$y=false;

Logic is often used for conditional testing. You'll learn more about conditional testing in the chapters later in this tutorial.

PHP arrays

An array stores multiple values in a variable.

In the following example, we will test different arrays. PHP Var_dump () returns the data type and value of the variable:

Instance

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<?php $cars=array("Volvo","BMW","SAAB");var_dump($cars);?>$myarr=array("one"=>"first","two"=>"second");foreach($myarras$key=>$value){    echo"Key:".$key."<br>"."Value:".$value."<br>";}

You'll learn more about arrays in the chapters later in this tutorial.

PHP Object

Objects are data types that store data and information about how to work with the data.

In PHP, you must explicitly declare an object.

First we must declare the class of the object. For this, we use the class keyword. A class is a structure that contains properties and methods.

We then define the data type in the object class, and then use this data type in an instance of the class:

Instance

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<?phpclassCar{    var$color;    functionCar($color="black"){        $this->color=$color;    }    function getcolor(){        return$this->color;    }}$aa=newCar();echo$aa->getcolor();?>

You will learn more about objects in the chapters later in this tutorial.

PHP NULL Value

A special NULL value indicates that the variable has no value. Null is the only possible value for the data type NULL.

The null value indicates whether the variable is empty. Also used to differentiate between empty strings and null-valued databases.

You can empty the variable by setting the value to NULL:

Instance

<?php$x= "Hello world!"; $x =null;var_dump ($x);? >

PHP Basic Tutorial-data types