PHP Variables

ᴰᵒᵖᵖᵉˡᵍᵃⁿᵍᵉʳ 多佩尔甘格尔

A variable in PHP is a name of memory location that holds data. A variable is a temporary storage that is used to store data temporarily.

In PHP, a variable is declared using $ sign followed by variable name.

Syntax of declaring a variable in PHP is given below:

$variablename=value;

PHP Variable: Declaring string, integer and float

Let's see the example to store string, integer and float values in PHP variables.

File: variable1.php

<?php  
$str="hello string";  
$x=200;  
$y=44.6;  
echo "string is: $str <br/>";  
echo "integer is: $x <br/>";  
echo "float is: $y <br/>";  
?>

Output:

string is: hello string

integer is: 200

float is: 44.6

PHP Variable: Sum of two variables

File: variable2.php

<?php  
$x=5;  
$y=6;  
$z=$x+$y;  
echo $z;  
?>

Output:

PHP Variable: case sensitive

In PHP, variable names are case sensitive. So variable name "color" is different from Color, COLOR, COLor etc.

File: variable3.php

<?php  
$color="red";  
echo "My car is " . $color . "<br>";  
echo "My house is " . $COLOR . "<br>";  
echo "My boat is " . $coLOR . "<br>";  
?>

Output:

My car is red

Notice: Undefined variable: COLOR in C:\wamp\www\variable.php on line 4

My house is

Notice: Undefined variable: coLOR in C:\wamp\www\variable.php on line 5

My boat is

PHP Variable: Rules

PHP variables must start with letter or underscore only.

PHP variable can't be start with numbers and special symbols.

File: variablevalid.php

<?php  
$a="hello";//letter (valid)  
$_b="hello";//underscore (valid)  
 
echo "$a <br/> $_b";  
?>

Output:

hello

File: variableinvalid.php

<?php  
$4c="hello";//number (invalid)  
$*d="hello";//special symbol (invalid)  
  
echo "$4c <br/> $*d";  
?>

Output:

Parse error: syntax error, unexpected '4' (T_LNUMBER), expecting variable (T_VARIABLE)

or '$' in C:\wamp\www\variableinvalid.php on line 2

PHP: Loosely typed language

PHP is a loosely typed language, it means PHP automatically converts the variable to its correct data type.

Report Page