PHP Variable
Variables in PHP
Variables are nothing its just containers that hold data or information. In other, word variable are just identifiers.
Important point about PHP variable
- It's used for storing information, like name, age place or anything.
- For example, you create a variable, like $name and store the value 38.
- The PHP variable names are case-sensitive.
PHP Variable Example
<?php $variable = 15; $variable_ab = 38; $sum = $variable + $variable_ab; echo " First value = ".$variable."
"; echo "Second value = ".$variable."
"; echo "sum = ".$sum; ?>
- Example
- Run
There are three variable in this example first is "variable", second is "variable_ab" and the third one is "sum". The value of variables displayed, perform an operation and store the value of on another variable named $sum and print.
Example of case sensitive variable
<?php $a=7; $A=38 ; echo $a ."<br>"; echo $A; ?>
Output
38
$a and $A are not same as shown in the above example. Because PHP variable name are case sensitive.
Rules for Variable Declaration
There are some simple rules for creating a PHP variable.
- A PHP variable must start with ($) dollar sign.
- A valid PHP variable name start with underscore ( _ ) or alphabet.
- The rest of variable name consist of alphanumeric character like acb1.
- PHP variable can any length.
- Uppercase letter is not equal to the lowercase letter.
- Not contain spaces
PHP Variable Declaration
A variable is a named memory location that contains data that may be manipulated throughout the execution of the script.
Some valid variable example
- $name
- $programming_1
- $_abc_variable
- $m
Example of PHP Variable Declaration
<?php $name="welcome to php"; // $12hj=12 //it's wrong echo $name; echo "
"; // $@12hj=12 //its wrong $first_value=12.30; $d1=450; echo "The first value:".$first_value; echo "
"; echo "The second value:".$d1; echo "
"; ?>
- Example
- Run
You can create PHP variable anywhere by using the dollar sign in our PHP script.
In this example $name is a string variable, $first_value is the integer value and $d1 is a float variable.
Displaying variable values
The fastest way to display the variable value, using print_r statement.
Using print_r
$name= "john"; print_r( $name );
using echo
$name= "john"; echo ( $name );
Example of variable declaration and initialization
<?php $var="Display the value using echo" ; $var1=" and print_r statements"; echo $var . $var1; echo "
"; $first_value=12.30; echo $first_value; $d1=450; echo "
"; print_r($d1); ?>
- Example
- Run
The following characters are not allowed in variable name
- asterisk (*)
- plus(+)
- hash(#)
- minus(-)
- ampersand(&)
- at the rate(@)
Another way to create variable
It's another method to create a variable using string constant to create a dynamic variable instead of a general variable.
Syntax
${"name_of_variable"} = "value";
Example of variable declaration
<?php
$var = "Variable creation=";
${"user"} = "bob";
print_r($var);
echo $user;
echo "
";
$a = date("Y/m/d") . "
";
echo "Todays date= ";
print_r($a);
?>
- Example
- Run
In this example we have explained the new way of creation of variable, $user is also a variable like other.
Delete PHP variable
You can use unset() function to destroy the variable. It takes one argument that is a variable name.
Delete variable example
<?php $brand = "Audi"; echo $brand; unset($brand); ?>
Output
In the above example $brand is a simple string type variable that hold the value Audi and print the variable and after use we can destroy the variable $brand an using unset function.
After destroying the variable, you cannot use that variable, if you use that variable, PHP displayed the notice like below shown.
Notice
Check type and length of variable
You can use var_dump( ) function to print the data type and the length of the variable as shown in below.
Check PHP Type Example
<?php $brand = "Audi"; var_dump ( $brand ); ?>
Output
You can also use gettype() function to check the type of variable.
