关于PHP代码的困惑

Question

Apologies if this is basic, but I'm learning php.

What does this snippet of code actually do? I've seen it in the source code for a plugin but can't quite figure out what's going on

$_POST['newName'] = $_POST['newName'] == "" ? "Dude" : $_POST['newName'];

Thanks.

Answer 1

This is a short version of if...else. This is a Ternary Logic .

$_POST['newName'] = $_POST['newName'] == "" ? "Dude" : $_POST['newName'];

if $_POST['newName'] == "" is true then "Dude" and else $_POST['newName'] .

and both the value will be set in $_POST['newName'] .

You can write this like this: [Full form]

if($_POST['newName'] == "") 
    $_POST['newName'] = "Dude";

Answer 2

The ? is also known as the ternary operator. It is called the ternary operator because it takes three operands - a condition, a result for true, and a result for false. If that sounds like an if statement to you, you are right on the money - the ternary operator is a shorthand (albeit very hard to read) way of doing if statements. Here's an example:

   <?php
   $agestr = ($age < 16) ? 'child' : 'adult';
    ?>

First there is a condition ($age < 16), then there is a question mark, and then a true result, a colon, and a false result. If $age is less than 16, $agestr will be set to 'child', otherwise it will be set to 'adult'. That one-liner ternary statement can be expressed in a normal if statement like this:

<?php
if ($age < 16) {
    $agestr = 'child';
} else {
    $agestr = 'adult';
}

?> So, in essence, using the ternary operator allows you to compact five lines of code into one, at the expense of some readability.

Answer 3

Sometimes while coding, you might feel that writing an if(...){...}else{...} might feel like overkill for small amounts of code:

$result;
if (20>3)
{
  $result = "bigger!";
}
else
{
  $result = "smaller!";
}

So for this reason, a short hand notation was created where you would be able to express the exact same statement but without the need for such a big structure:

$result = (20>3) ? "bigger!" : "smaller!" ;

Whatever is between = and ? would then be the condition that is normally between the ( and ) of if(...) . If that expression then equates to true , the value obtained by $result would be: "bigger!" , and if it equated to false , the result would be: "smaller!" .

Answer 4

As Frayne said, it is the shortened version of conditional statement. When we write it in full form, it becomes this:

<?php
    if($_POST['newName'] == "") {
        $_POST['newName'] = "Dude";
    } else {
        $_POST['newName'] = $_POST['newName'];
    }