What does null mean? Analysis of the difference between unset and null when deleting variables in PHP

First method: $varname=null
Second method: unset($varname)
Both methods can delete variables, but the results are slightly different.
Code:

Copy code The code is as follows:

$a = array(
'a' => 'a',
'b' => 'b'
) ;
$b = array(
'a' => 'a',
'b' => 'b'
);
$a['b'] = null;
unset($b['b ']);
print('

'); 
print_r($a); 
print('
'); 
print_r($b); 
print('?> 


Result: 
Copy code  The code is as follows: 

Array 
( 
[a] => a 
[b] => 
) 
Array 
 ( 
[a] => a 
) 

                
                
                

                    The above has introduced what null means. An analysis of the difference between unset and null when deleting variables in PHP, including what null means. I hope it will be helpful to friends who are interested in PHP tutorials.