PHP Variables

PHP Variables

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:


PHP Variable: Declaring String, Integer and Float

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

    $str="hello string";  
    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

    echo $z;  
Output : 11

PHP Variable: Case Sensitive

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

    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.

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

Invalid Rules

    $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.