Why empty string not working but null works perfectly?

Question

I just want to make a GET request in php and here is my requirement,

URL: http://localhost/test.php?firstName=Sagar&secondName=Gautam

Expected Output: Hi Sagar Gautam

URL: http://localhost/test.php

Expected Output: Hi Guest

Here is the code

test.php

<?php 
    $firstName = $_GET['firstName'];
    $secondName = $_GET['secondName'];

    $response = '';

    if($firstName!='' && $secondName!='')
    {
        $response = "Hi ".$firstName.' '.$secondName;
    }
    else
    {
        $response = "Hi Guest";
    }

    echo $response;
?>

Above code doesn't work but when I change empty string to null in if statement like this

if($firstName!=null && $secondName!=null)

then everything works perfectly.

I've already visited this question: In PHP, what is the differences between NULL and setting a string to equal 2 single quotes but don't get idea why above code not work with empty string.

If somebody explain whats going wrong, it will be great.

Answer 1

It's better to check isset() the $_GET variables

$firstName = isset($_GET['firstName']) ? $_GET['firstName'] : '';
$secondName = isset($_GET['secondName']) ?  $_GET['firstName']: '';

We always get the not null value.

Just a small note: isset will take care null case for you too. isset($null_value) -> false

Answer 2

Try This

if($firstName!=='' && $secondName!=='')

Hope This Help