PHP

PHP Variables

March 02, 2022

Php Variables: Variables is a name of storage space which is used to store data. Its value may be changed. It always contains the last value stored to it. Variables is a container which holds the value. Variable in PHP starts with dollar($) sign. In PHP, a variable is declared using a $ sign followed by the variable name. Here, some important points to know about variables.

As PHP is a loosely typed language, so we do not need to declare the data types of the variables.

It automatically analyzes the values and makes conversions to its correct datatype. After declaring a variable, it can be reused throughout the code. Assignment Operator (=) is used to assign the value to a variable.

Type-1
Local variable or user defined variable.

Syntax- $VARIABLE_NAME

Type-2
Global variables or pre-defined variables
a) $GLOBAL => To create a php global variable.

b) $_POST => To access value from a HTML form using 'post' method.

c) $_GET => To access value from a HTML form using 'get' method.

d) $_REQUEST => To access value from a HTML form using any method.

e) $_SERVER => To get data related to server.

f) $_SESSION => To create session storage.

g) $_COOKIE => To create a local storage.

h) $_ENV => To get or update data in PHP environment.

i. $_FILES => To access file details from a HTML form and upload to the server.

What are the rules to declare variable in PHP?

  • It must start with the dollar sign.
  • There is no need of data type (int, float, char) to define a variable.
  • Variables can, but do not need, to be declared before assignment.
  • After the dollar sign, the first letter of a variable should be alphabet or underscore(_).
  • After the dollar sign, the first letter of a variable should not be a digit.
  • After the first character, it may be a combination of alphabets and digits.
  • Blank spaces are not allowed in variable name.
  • A variable must start with a dollar ($) sign, followed by the variable name.
  • It can only contain alphanumeric character and underscore (A-z, 0-9, _).
  • A variable name must start with a letter or underscore (_) character.
  • A PHP variable name cannot contain spaces.
  • One thing to be kept in mind that the variable name cannot start with a number or special symbols.
  • PHP variables are case-sensitive, so $name and $NAME both are treated as different variable.