Variable Introduction -: Like other language a variable in php store the temporary data.A variable data name that may be used to store a data value only constant that remain unchanged during the execution of a program a variable may take different values at different times during execution we used several variable.
Variable store the value of money at the end of each year A variable name can be chosen by the programmer in a meaningful way so as to replace function or nature in the program some example of some names are here height, Total, weight, amount etc.
How to declare a variable in php language -: Before we use the variable it is necessary to declare a variable. In the PHP language a variable is declare using the Dollar sign ($). For example
$variable name = value; $ x =5 ; //here x is the variable name and 5 is the value of x
There are 2 main variable are use in the php language. These are the
1-: Single dollar sign($)- In this type simple variable are use as like
2-: Double dollar sign ($$) – In this type variable a special reference variable stores the value of the $variable inside it.
Example of single variable -:
<?php $str="hello netnic"; $a=100; $b=22.6; echo "string is: $str <br/>"; echo "integer is: $a <br/>"; echo "float is: $b <br/>"; ?>
output of this programe
string is:hello netnic integer is: 100 float is: 22.6
how to add two variable in php –: we can easily add two variable in php language. see the example here
<?php $a=10; $b=22; $c=$a+$b; echo $c ; ?>
Output of this program
Rules for variable in php –: Like any other programming language there are some rules for declaring a variable in php these are the
- A variable name is case sensitive means color and Color are different. These are two variable.
- A php variable start with letter or underscore. like $ x, $-netnic, etc.
- Keyword are not use in variable name.
Write a program to double variable -:
<?php $a = "netnic"; $$a = 500; echo $a"<br/>"; echo $$a"<br/>"; echo $netnic; ?>
Output of this programe
netnic 500 500