布尔值相当于PHP中的NULL

Question

is this the right syntax to check if a value is equivalent to NULL or not in PHP:

if($AppointmentNo==NULL)

? I have tried it but it seems that it is not working. Any suggestion for another syntax?

Thanks

Answer 1

Use is_null():

if(is_null($AppointmentNo)) {

// do stuff

}

Alternatively, you could also use strict comparison (===):

if($AppointmentNo === NULL) {

An example:

$foo = NULL;

if(is_null($foo)) {
    echo 'NULL';
} else {
    echo 'NOT NULL';
}

Output:

NULL