Why check isset () and! Empty () in PHP?

PHP

Syntax:
bool isset ($var, mixed) 
Parameters:This function takes more than one parameter. The first parameter of this function - $var. This parameter is used to store the value of a variable.Example :  
// PHP illustration program
// isset() function $num = '0' ; if (isset ( $num )) { print_r ( " $num is set with isset function < br > " ); }  
// Declare an empty array $array = array ();  
// Using the isset function echo isset ( $array [ 'engineer' ])? 'array is set.' : 'array is not set.' ; ?>
Exit:
0 is set with isset function 
array is not set. 
empty() function
The empty() function is a language construct to determine if a given variable is empty or NULL. Function! Empty() is the negation or complement of the empty() function. The empty() function is significantly equal to the function! Isset(), and the function! Empty() is equal to isset().Example :  
// PHP illustration program
// empty() function $temp = 0;  
// returns true because // $temp is empty if ( empty ( $temp ) ) { echo $temp . 'is considered empty' ; } echo "" ;  
// Returns true because $new exists $new = 1; if (! empty ( $new )) { echo $new . 'is considered set' ; }
?>
Exit:
0 is considered empty 1 is considered set 
Reason to check both functions:
The isset() and! Empty() are similar and both will return the same results. But the only difference is that! The Empty() function will not generate any alerts or email notifications when the variable does not exist. It is enough to use any of the functions. Including both functions in a program results in slower times and unnecessary memory usage.Example : < ? php  
// PHP function for demonstration isset()
// and! empty() function 
// Initialize the variable $num = '0' ;  
// Checking the isset() function if (isset ( $num )) { print_r ( $num . " is set with isset function " ) ; }  
// Show new line echo "" ;  
// Initialize the variable $num = 1;  
// Checking the function! Empty() if (! empty ( $num )) { print_r ( $num . " is set with! empty function " ); } Exit :
0 is set with isset function 1 is set with! empty function