We have given a variable and the task is to check whether a variable var is set or not in PHP. In order to do this task, we have the following methods in PHP:
Approach 1: Using isset() Method: The isset() method returns True if the variable is declared and its value is not equal to NULL.
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Syntax:
bool isset( mixed $var [, mixed $... ] )
Example :
PHP
<?php // PHP program to check whether // a variable is set or not     $str = "neveropen";     // Check value of variable is set or not if(isset($str)) {     echo "Value of variable is set"; } else {     echo "Value of variable is not set"; } ?> |
Output
Value of variable is set
Approach 2: Using !empty() Method: The empty() method returns True if the variable is declared and its value is equal to empty and not a set.
Syntax:
bool empty( $var )
Example :
PHP
<?php // PHP program to check whether // a variable is set or not     $str = "neveropen";     // Check value of variable is set or not if(!empty($str)) {     echo "Value of variable is set"; } else {     echo "Value of variable is not set"; } ?> |
Output
Value of variable is set
Approach 3: Using !is_null() Method: The is_null() method returns True if the variable is declared and its value is equal to Null and not a set.
Syntax:
bool empty( $var )
Example :
PHP
<?php // PHP program to check whether // a variable is set or not     $str = "neveropen";     // Check value of variable is set or not if(!is_null($str)) {     echo "Value of variable is set"; } else {     echo "Value of variable is not set"; } ?> |
Output
Value of variable is set
