PHP Data Types and Variables — string, int, bool

PHP Variables

Variables are "containers" for storing information. A variable can be used to hold values (eg. x=5) and expression (eg. z=x+y). PHP has no command for declaring a variable. We have to assign value to the PHP variable, while the creation of variable. If we want to create variable without assigning a value to it, then we assign NULL value to it. Generally in PHP, a variable does not need to be declared before adding a value to it.

Standard Rules for PHP Variable Names

Variable in PHP starts with a $ sign, followed by the name of the variable.
The variable name in PHP must begin with a alpha-numeric character or the underscore character i.e.(A-Z, a-z, 0-9, and underscore).
A variable name should not contain blank spaces.
A variable names are case sensitive i.e.($Y and $y are two different variable).

Scope of PHP Variables

Each variable has an area in which it exist, known as its scope PHP has four different variable scope:-

Local Scope:- A variable declared within a any PHP function is local and can only be accessed within that function.

example

<?php
    $X=5 //Global
	
	function myFun() {
		echo $X //Local
	}
	
	myFun();
?>

The above script will not give any output, because the echo statement refers to the local scope.

Key Takeaways

PHP is dynamically typed - variables automatically take the type of the value assigned.
Use gettype() to check a variable's type and settype() to convert it.
PHP has 8 primitive types: int, float, string, bool, array, object, null, and resource.
Variable names start with $ and are case-sensitive - \ and \ are different variables.
Use var_dump() for debugging - it shows both the type and value of a variable.
Type juggling (automatic type conversion) can cause unexpected behavior - use strict comparison (===) to avoid it.