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PHP 5 Power Programming by Derick Rethans, Stig Sæther Bakken, Andi Gutmans

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2.4. Variables

Variables in PHP are quite different from compiled languages such as C and Java. This is because their weakly typed nature, which in short means you don't need to declare variables before using them, you don't need to declare their type and, as a result, a variable can change the type of its value as much as you want.

Variables in PHP are preceded with a $ sign, and similar to most modern languages, they can start with a letter (A-Za-z) or _ (underscore) and can then contain as many alphanumeric characters and underscores as you like.

Examples of legal variable names include

$count
$_Obj
$A123

Example of illegal variable names include

$123
$*ABC

As previously mentioned, you don't need to declare variables or their type before ...

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