PHP Variable

What is variable?

A variable is an identifier for a piece of data stored in memory during the program execution. In PHP, variables are used under basic rules:

A variable name in PHP must be prefixed with a “$” sign. Perl has a similar rule for scale variables.

Variable names are case sensitive. So $abdul and $Abdul refer to two different variables.

Variables in PHP are typeless. Therefore there is no variable type declaration statements in PHP. Any variable can be used as the identifier for any data type.

& operator returns the reference of a variable.

The reference of a variable can be assigned to a new variable to make an alias to the original variable.

A variable name can be represented as a string expression. This is called variable variable name.

Functions define() defines a constant with the constant name and the constant value.

Only scalar data type values can be used as constant values.

A variable has 2 states: “set” and “unset”. A variable is in the “set” state, if a piece of data has been assigned to it. A variable is in the “unset” state, if there is no data assigned to it.

Assignment operations (coded by the assignment operator, =) can be used to assign data to variables.

The unset ($var) function can be used to remove the assigned data from the given variable.

Variables can used in any operations like data literals in PHP source code. If a variable with data assigned is used in an operation, the assigned data value will be used for the operation. If a variable with no data assigned is used in an operation, NULL will be used for the operation.

There are some special characters that you should not use them as a part of a variable name, ‘ ‘, ‘$’, ‘[‘, ‘]’, ‘{‘, ‘}’, …

PHP has a nice built in function, var_dump($var), that prints out detailed information about the specified variable.

To show you some of variable rules mentioned above, I wrote the PHP program name Variables.php

Click on the below link to download the file:

 http://bit.ly/2GMjrdA