What does double question mark operator mean in PHP

0 votes

 This piece of code:

$env = $_SERVER['APP_ENV'] ?? 'dev';

I'm not pretty sure what this actually does but I imagine that it expands to something like:

$env = $_SERVER['APP_ENV'] != null ? $_SERVER['APP_ENV'] : 'dev';

Or maybe:

$env = isset($_SERVER['APP_ENV']) ? $_SERVER['APP_ENV'] : 'dev';

Can anyone help me out wuth this?

Apr 2, 2020 in PHP by kartik
• 37,490 points
1,428 views

1 answer to this question.

0 votes

Hello,

It's the "null coalescing operator", added in php 7.0. The definition of how it works is:

It returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

So it's actually just isset() in a handy operator.

Those two are equivalent1:

$foo = $bar ?? 'something';
$foo = isset($bar) ? $bar : 'something';

Thank You!!

answered Apr 2, 2020 by Niroj
• 82,580 points

Related Questions In PHP

0 votes
1 answer

What is the use of $_REQUEST variable in php?

Hii @kartik, The $_REQUEST variable is used to read the ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
226 views
0 votes
0 answers

What are the differences in die() and exit() in PHP?

I think both have the same functionality, ...READ MORE

Apr 8, 2020 in PHP by kartik
• 37,490 points
111 views
0 votes
1 answer

What is the use of the @ symbol in PHP?

Hello @kartik, The @ symbol is the error control operator ("silence" or "shut-up" ...READ MORE

answered Apr 8, 2020 in PHP by Niroj
• 82,580 points
728 views
0 votes
2 answers

Define a SQL query? What is the difference between SELECT and UPDATE Query? How do you use SQL in SAS?

HI.. SQL is Structured Query Language, which is ...READ MORE

answered Aug 8, 2020 in PHP by anonymous
1,997 views
0 votes
1 answer

Why it is necessary to refresh CSRF token per form request?

Hello, Generating a new CSRF token for each ...READ MORE

answered Mar 19, 2020 in Laravel by Niroj
• 82,580 points
1,585 views
0 votes
1 answer

Connection with MySQL server using PHP. How can we do that?

Hey @kartik, You have to provide MySQL hostname, ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
151 views
0 votes
1 answer

How to retrieve or obtain data from the MySQL database using PHP?

Hello kartik,  Actually there are many functions that  ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
284 views
0 votes
1 answer

What are the differences between mysqli_connect and mysqli_pconnect?

Hello, mysqli_pconnect() function is used for making a persistence ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
752 views
0 votes
1 answer

What is meant by passing the variable by value and reference in PHP?

Hello, When the variable is passed as value ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
298 views
0 votes
1 answer

What is type casting and type juggling in php?

Hey, The way by which PHP can assign ...READ MORE

answered Mar 27, 2020 in PHP by Niroj
• 82,580 points
928 views