Php variables declaration || how to declare php variables

How to declare PHP Variables 

Php variables are declared in $ simple and name

Example

         $name="value";

      The letters is "" double are '' single quotes

Declare to correct way

      The digits declare no quotes

       

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:

1. $variablename=value;  

PHP Variables: Declaring string, integer and floating-point

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

File: variable1.php

1. <?php  
2. $str="hello string";  
3. $x=200;  
4. $y=44.6;  
5. echo "string is: $str <br/>";  
6. echo "integer is: $x <br/>";  
7. echo "float is: $y <br/>";  
8. ?>  

Output:

string is: hello string
integer is: 200
float is: 44.6 

PHP Variable: Sum of two digits

File: variable2.php

1. <?php  
2. $x=5;  
3. $y=6;  
4. $z=$x+$y;  
5. echo $z;  
6. ?>  

Output:

11

PHP Variable: case sensitive

Php capital letters and small letters consider 

Different types

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

File: variable3.php

1. <?php  
2. $color="red";  
3. echo "My car is " . $color . "<br>";  
4. echo "My house is " . $COLOR . "<br>";  
5. echo "My boat is " . $coLOR . "<br>";  
6. ?>  

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

1. <?php  
2. $a="hello";//letter (valid)  
3. $_b="hello";//underscore (valid)  
4.   
5. echo "$a <br/> $_b";  
6. ?>  

Output:

hello 
hello