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[edit] Last updated: Fri, 20 Apr 2012

Types

Table of Contents

Introduction

Booleans

Integers

Floating point numbers

Strings

Arrays

Objects

Resources

NULL

Callbacks

Pseudo-types and variables used in this documentation

Type Juggling

User Contributed Notes Types

Jeffrey 26-Oct-2008 10:31

The Object (compound) Type

Like every programming language, PHP offers the usual basic primitive types which can hold only one piece of data at a time (scalar). I am

particularly fond of the "object" type (compound) because that allows me to group many basic PHP types together, and I can name it anything

I want.

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$hasDriversLicense; // a PHP Boolean

}

?>

Here, I have grouped several basic PHP types together, (3) Strings, (1) Integer, and (1) Boolean... then I named that group "Person". Since

I used the proper syntax to do so, this code is pure PHP, which means that if you run this code, you would have an extra PHP "type"

available to you in your scripts, like so:

You can make your own object types and have PHP execute it as if it were part of the PHP language itself. See more on classes and objects

in this manual at: http://www.php.net/manual/en/language.oop5.php

arjini at gmail dot com 06-Dec-2005 12:32

Note that you can chain type castng:

var_dump((string)(int)false); //string(1) "0"

shahnaz khan 18-Mar-2005 04:40

if we use gettype() before initializinf any variable it give NULL

for eg.

it will show

NULL

Trizor of www.freedom-uplink.org 29-Jun-2004 06:14

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The differance of float and double dates back to a FORTRAN standard. In FORTRAN Variables aren't as loosly written as in PHP and you had to

define variable types(OH NOES!). FLOAT or REAL*4 (For all you VAX people out there) defined the variable as a standard precision floating

point, with 4 bytes of memory allocated to it. DOUBLE PRECISION or REAL*8 (Again for the VAX) was identical to FLOAT or REAL*4, but with an

8 byte allocation of memory instead of a 4 byte allocation.

In fact most modern variable types date back to FORTRAN, except a string was called a CHARACHTER*N and you had to specify the length, or

CHARACHTER*(*) for a variable length string. Boolean was LOGICAL, and there weren't yet objects, and there was support for complex

numbers(a+bi).

Of course, most people reading this are web programmers and could care less about the mathematical background of programming.

NOTE: Object support was added to FORTRAN in the FORTRAN90 spec, and expanded with the FORTRAN94 spec, but by then C was the powerful force

on the block, and most people who still use FORTRAN use the FORTRAN77.

Copyright 2 001-2012 The PHP GroupAll rights reserved.

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