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Php declaration of variables
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- PHP SplObjectStorage count() Function
- PHP SplQueue::__construct() Function
- PHP SPL Data structures Complete Reference
- PHP Tutorial
- PHP | Introduction
- PHP Full Form
- How to set PHP development environment in windows ?
- LAMP installation and important PHP configurations on Ubuntu
- PHP | Coding Standards
- PHP | Basic Syntax
- PHP | Variables
- PHP echo and print
- PHP | Data Types
- PHP | Strings
- PHP | Constants
- PHP | Magic Constants
- PHP | Decision Making
- PHP | Loops
- PHP | Superglobals
- PHP | Regular Expressions
- PHP Examples
- Describe PHP Include and Require
- PHP | Basics of File Handling
- PHP | fopen( ) (Function open file or URL)
- PHP fread( ) Function
- PHP fclose( ) Function
- PHP | fwrite( ) Function
- PHP | Uploading File
- PHP Cookies
- PHP | Sessions
- PHP Filter and Filter Constant
- Implementing callback in PHP
- Exception Handling in PHP
- PHP | Arrays
- PHP array() Function
- PHP | array_change_key_case() Function
- PHP array_chunk() Function
- PHP | array_column() Function
- PHP array_combine() Function
- PHP array_count_values() Function
- PHP array_diff() function
- PHP array_diff_assoc() Function
- PHP array_diff_key() Function
- PHP array_diff_uassoc() Function
- PHP array_diff_ukey() Function
- PHP array_fill() function
- PHP array_fill_keys() Function
- PHP Array Functions Complete Reference
- PHP Date and Time
- PHP | checkdate() Function
- PHP | date_create(), date_format(), date_add() Functions
- PHP | date_create_from_format() Function
- PHP | date_date_set() Function
- PHP | date_default_timezone_get() Function
- PHP | date_default_timezone_set() Function
- PHP | date_diff() Function
- PHP | date_get_last_errors() Function
- PHP | date_isodate_set() Function
- PHP | date_modify() Function
- PHP | date_offset_get() Function
- PHP | date_parse_from_format() Function
- PHP | date_parse() Function
- PHP | date_sub() Function
- PHP basename( ) Function
- PHP chgrp( ) Function
- PHP chmod( ) Function
- PHP chown( ) Function
- PHP copy( ) Function
- PHP dirname( ) Function
- PHP disk_free_space( ) Function
- PHP disk_total_space( ) Function
- PHP feof( ) Function
- PHP fflush( ) Function
- PHP | fgetc( ) Function
- PHP | fgets( ) Function
- PHP | fgetss( ) Function
- PHP | file_exists( ) Function
- PHP file_get_contents() Function
- PHP Filesystem Functions Complete Reference
- PHP | ftp_alloc() function
- PHP | ftp_chdir() function
- PHP | ftp_close() function
- PHP | ftp_connect() function
- PHP | ftp_delete() function
- PHP | ftp_exec() function
- PHP | ftp_get() function
- PHP | ftp_put() function
- PHP | ftp_get_option() function
- PHP | ftp_login() function
- PHP | ftp_mdtm() Function
- PHP | ftp_mkdir() function
- PHP | Ds\Map allocate() Function
- PHP | Ds\Map apply() Function
- PHP | Ds\Map capacity() Function
- PHP | DS\Map clear() Function
- PHP | Ds\Map __construct() Function
- PHP Ds\Map copy() Function
- PHP | Ds\Map count() Function
- PHP | Ds\Map diff() Function
- PHP | Ds\Map filter() Function
- PHP | Ds\Map first() Function
- PHP Ds\Map Functions Complete Reference
- SplDoublyLinkedList in PHP
- PHP SplDoublyLinkedList add() Function
- PHP SplDoublyLinkedList bottom() Function
- PHP SplDoublyLinkedList count() function
- PHP SplFixedArray count() Function
- PHP SplFixedArray current() Function
- PHP SplFixedArray getSize() Function
- PHP SplFixedArray key() Function
- PHP SplObjectStorage addAll() Function
- PHP SplObjectStorage attach() Function
- PHP SplObjectStorage contains() Function
- PHP SplObjectStorage count() Function
- PHP SplQueue::__construct() Function
- PHP SPL Data structures Complete Reference
PHP Variables
In PHP, a variable starts with the $ sign, followed by the name of the variable:
Example
After the execution of the statements above, the variable $txt will hold the value Hello world! , the variable $x will hold the value 5 , and the variable $y will hold the value 10.5 .
Note: When you assign a text value to a variable, put quotes around the value.
Note: Unlike other programming languages, PHP has no command for declaring a variable. It is created the moment you first assign a value to it.
Think of variables as containers for storing data.
PHP Variables
A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).
- A variable starts with the $ sign, followed by the name of the variable
- A variable name must start with a letter or the underscore character
- A variable name cannot start with a number
- A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
- Variable names are case-sensitive ( $age and $AGE are two different variables)
Remember that PHP variable names are case-sensitive!
Output Variables
The PHP echo statement is often used to output data to the screen.
The following example will show how to output text and a variable:
Example
The following example will produce the same output as the example above:
Example
The following example will output the sum of two variables:
Example
Note: You will learn more about the echo statement and how to output data to the screen in the next chapter.
PHP is a Loosely Typed Language
In the example above, notice that we did not have to tell PHP which data type the variable is.
PHP automatically associates a data type to the variable, depending on its value. Since the data types are not set in a strict sense, you can do things like adding a string to an integer without causing an error.
In PHP 7, type declarations were added. This gives an option to specify the data type expected when declaring a function, and by enabling the strict requirement, it will throw a «Fatal Error» on a type mismatch.
You will learn more about strict and non-strict requirements, and data type declarations in the PHP Functions chapter.