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.
Syntax of declaring a variable in PHP is given below:
$variablename=value;
Rules for declaring PHP variable:
- A variable must start with a dollar ($) sign, followed by the variable name.
- It can only contain alpha-numeric 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.
PHP Variable: Declaring string, integer, and float
Let’s see the example to store string, integer, and float values in PHP variables.
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Variables</title> </head> <body> <?php $str="hello string"; $x=200; $y=44.6; echo "string is: $str <br/>"; echo "integer is: $x <br/>"; echo "float is: $y <br/>"; ?> </body> </html> |
Output:
string is: hello string
integer is: 200
float is: 44.6
PHP Variable: Sum of two variables
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Variables</title> </head> <body> <?php $x=4; $y=6; $z=$x+$y; echo $z; ?> </body> </html> |
Output:
10
PHP Variable: case sensitive
In PHP, variable names are case sensitive. So variable name “color” is different from Color, COLOR, COLor etc.
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>case sensitive</title> </head> <body> <?php $color="red"; echo "My car is $color <br>"; echo "My book is $COLOR <br>"; echo "My shirt is $coLOR <br>"; ?> </body> </html> |
Output:
My car is red
Notice: Undefined variable: COLOR in C:\xampp\htdocs\dkyadav\index.php on line 11
My book isNotice: Undefined variable: coLOR in C:\xampp\htdocs\dkyadav\index.php on line 12
My shirt is
PHP Variable: Rules
- PHP variables must start with letter or underscore only.
- PHP variable can’t be start with numbers and special symbols.
- $a=“hello”;//letter (valid)
- $_b=“hello”;//underscore (valid)
- $4c=“hello”;//number (invalid)
- $*d=“hello”;//special symbol (invalid)
