The isset() function is an inbuilt function in PHP which is used to determine if the variable is declared and its value is not equal to NULL.
Syntax:
bool isset( mixed $var [, mixed $... ] )
Parameters: This function accept one or more parameter as mentioned above and described below:
- $var: It contains the variable which need to check.
- $…: It contains the list of other variables.
Return Value: It returns TRUE if var exists and its value not equal to NULL and FALSE otherwise.
Below examples illustrate the isset() function in PHP:
Example 1:
<?php
$str = "GeeksforGeeks" ;
if (isset( $str )) {
echo "Value of variable is set" ;
}
else {
echo "Value of variable is not set" ;
}
$arr = array ();
if ( !isset( $arr [0]) ) {
echo "\nArray is Empty" ;
}
else {
echo "\nArray is not empty" ;
}
?>
|
Output:
Value of variable is set
Array is Empty
Output:
Example 2:
<?php
$num = 21;
var_dump(isset( $num ));
$arr = array (
"a" => "Welcome" ,
"b" => "to" ,
"c" => "GeeksforGeeks"
);
var_dump(isset( $arr [ "a" ]));
var_dump(isset( $arr [ "b" ]));
var_dump(isset( $arr [ "c" ]));
var_dump(isset( $arr [ "Geeks" ]));
?>
|
Output:
bool(true)
bool(true)
bool(true)
bool(true)
bool(false)
Reference: https://www.php.net/manual/en/function.isset.php
Last Updated :
27 Apr, 2020
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