Checking set and unset variable

isset : 

isset : is set return true or false for weather if a varible is defined or not

<?php

$x=10;

var_dump(isset($x));

?>

unset : 

unset : same reverse of isset it destroys the defined varible or key.

<?php

echo "<hr/>";

$b='ravi';

echo "<hr/>";

echo $b;

echo "<hr/>";

var_dump(isset($b));

echo "<hr/>";

unset($b); // destroy

echo $b; // undefined Index $b : Notice Error

echo "<hr/>";

var_dump(isset($b));

?>

How to set default value to a undefined varible

we are going to use ternary Operator for such logic

General Syntax:

---------------

<expression>?[true]:[false];

<?php

$x=5;

($x%2==0)?print("even"):print("odd");

//it is short version of if-else

?>

if value is unset then undefined index error will raise.

we need to handle that 

 there are two possible ways : 

1. suppress Operator @

2. using Ternary to handle unset varible

1. Suppress Operator : (@) is used to hide Notice or Warning Error

2. Ternary Operator: can be to assign a default value if they not defined

 

Special Care must be taken for Get Varible