Isset function
ISSET checks the variable to see if it has been set. In other words, it checks to see if the variable is any value except NULL or not assigned a value. ISSET returns TRUE if the variable exists and has a value other than NULL. That means variables assigned a "", 0, "0", or FALSE are set, and therefore are TRUE for ISSET.
Example
<?php
$val = '0';
if( isset($val)) {
print_r(" $val is set with isset function <br>");
}
$my_array = array();
echo isset($my_array['New_value']) ?
'array is set.' : 'array is not set.';
?>Output
This will produce the following output −
0 is set with isset function array is not set.
!empty function
EMPTY checks to see if a variable is empty. Empty is interpreted as: "" (an empty string), 0 (integer), 0.0 (float)`, "0" (string), NULL, FALSE, array() (an empty array), and "$var;" (a variable declared, but without a value in a class.
Example
<?php
$temp_val = 0;
if (empty($temp_val)) {
echo $temp_val . ' is considered empty';
}
echo "nn";
$new_val = 1;
if (!empty($new_val)) {
echo $new_val . ' is considered set';
}
?>Output
This will produce the following output −
0 is considered empty 1 is considered set