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
Last update: 531 days ago
