Php
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Variables
- 1 Basics 5
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Quotes S
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Constants S
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Control structures S
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Reference S
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- 2 Variables 4
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Definition S
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Variable variable S
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Exists S
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Type casting S
- 3 Operators 5
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Aritmetic S
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Bitwise S
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String S
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Comparison S
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Logical S
- 4 Function 4
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Definition S
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Anonymous S
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Reference S
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Variable arguments S
- 5 Array 7
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Basics S
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Create S
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Search S
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Modify S
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Sort S
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Storage S
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Basics
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Compare
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Replace
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Format
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Regexp
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Formating
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Json
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Ob_start
- 8 Oop 6
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Object instantiation S
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Class constructor
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Interfaces, abstract
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Resource visibility
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Class constants
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Autoload
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PHPUNIT
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Php7.4 S
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- 11 Http 4
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Headers
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- 12 Design Patterns 4
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Observer Pattern
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- 13 Modern Php 8
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Composer S
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Slim Framework
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Symfony v5
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- 17 Symfony 6
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Routes S
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Flex
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Doctrine
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Templating
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Q
Php Variables Definition
Php implicitly changes types as needed Variables names are case sensitive $name = 'John' echo $Name; // Undefined variable: NameVariables
Type
PHP will implicitly change the type of a variable as needed (loosely typed).
/**
* PHP will implicitly ...
* change the type of a variable as needed
*
* This contrasts with strongly typed languages,
* like C and Java
*/
$a = "abc";
$b = 0 + "1";
$c = new ArrayObject();
echo gettype($a); // string
echo gettype($b); // integer
echo gettype($c); // object
Naming
Variables must start with a letter or an underscore.
/**
* Variables must be named using only ...
* letters, numbers and underscore.
* $name_/ - invalid name
*
* Variables must start with a letter or an underscore
* $1_name - invalid start
*/
$name = 'valid'; // valid name
$_name = 'valid'; // valid start
Case
Variables names are case sensitive.
/**
* In PHP Variables are one of only two identifier types ...
* that are case-sensitive
*
* The other are constants
*/
$Name = "John";
const NAME = "Bob";
var_dump(isset($name)); // false
//echo name;
//Undefined constant: name
➥ Questions