Variables in PHP

variables in php

declaring variables in php is very simple .its more easier then java and c++ to declare variable

•PHP variables must begin with a “$” sign

ie $x , $y

•Case-sensitive

($Foo != $foo != $fOo)

•Global and locally-scoped variables

–Global variables can be used anywhere
–Local variables restricted to a function or class

•Certain variable names reserved by PHP

–Form variables ($_POST, $_GET)
–Server variables ($_SERVER)
–Etc.

•PHP is a loosely typed language

–In PHP, a variable does not need to be declared before adding a value to it
Example code
[code start]

<?php

$foo = 25; // Numerical variable
$bar = “Hello”; // String variable

$foo = ($foo * 7); // Multiplies foo by 7
$bar = ($bar * 7); // Invalid expression

[code end]

Echo in php

•The PHP command ‘echo’

is used to output the parameters passed to it
–The typical usage for this is to send data to the client’s web-browser

•Syntax

–void echo (string arg1 [, string argn...])
–In practice, arguments are not passed in parentheses since echo is a language construct rather than an actual function

Example:

[code start]

<html>

<body>

<?php

echo "Hello World";

<br />

<?php

$txt="Hello World";

echo $txt;

</body>

</html>

[code end]

Example2:

[code start]

<?php

$foo = 25; // Numerical variable
$bar = “Hello”; // String variable

echo $bar; // Outputs Hello

echo $foo,$bar; // Outputs 25Hello

echo “5x5=”,$foo; // Outputs 5x5=25

echo “5x5=$foo”; // Outputs 5x5=25
echo ‘5x5=$foo’; // Outputs 5x5=$foo

[code start]

•Notice how echo ‘5x5=$foo’ outputs $foo rather than replacing it with 25
•Strings in single quotes (‘ ’) are not interpreted or evaluated by PHP
•This is true for both variables and character escape-sequences (such as “\n” or “\\”)