In-depth analysis of the "? :" operator in PHP and its usage!

This article will give you an in-depth analysis of the "? :" operator (ternary expression) in PHP to see its function, how to use it, and what is the effect? I hope to be helpful!

What are the ? and : operators in PHP? ?

is as follows:

(($request_type == 'SSL') ? HTTPS_SERVER : HTTP_SERVER)

It is a conditional operator.

$x ? $y : $z

means "If $x is true, then use $y; if not, use $z".

It can also be simplified.

$x ?: $z

means "If $x is true, then use $x; if not, use $z".

Some people would say ?: is the "ternary operator". this is not right. ?: If it is a ternary operator, then it should have three operands. The reason for this is that it is generally the only ternary operator in current languages.

The following will introduce what ternary is, how to use it, when to use it, why to use it, and when not to use it.

What is the ternary operator?

? : is the abbreviation of if and else. There is an official description of the "ternary operator" in the middle.

Since PHP 5.3:

Starting from PHP 5.3, the middle part of the ternary operator can be omitted. The expression expr1 ?: expr3 returns expr1 if expr1 is TRUE and expr3 otherwise.

Since PHP 7.0

PHP 7 has new Null coalescing operator. This is the same as the ternary operator, also known as the "isset ternary operator". This removes isset() from chained ternary arithmetic.

In PHP 5, if you use the ternary operator on a variable that may not exist, you must use isset() at the beginning of the ternary statement:

$result = isset($nonExistentVariable) ? $nonExistentVariable : ‘default’;

In In PHP 7, you can do this:

$result = $nonExistentVariable ?? ‘default’;

Remember that the Null coalescing operator cannot handle empty strings. You can use it in a chain to check multiple variables:

$user = $userImpersonatingAnotherUser ?? $loggedInUser ?? “Guest”;

In PHP, it is not uncommon for administrators to pretend to be users for testing on systems that can be logged in. As above, if the user is not impersonating another user and is not logged in, he will become a guest. If you still don’t understand, continue reading to learn what the ternary operator is and how to use it. Then go back and see how to use the ternary operator in the new PHP

symbol?

Normal if The statement is as follows:

if (isset($_POST['hello']))
{
    $var = 'exists';
}
else
{
    $var = 'error';
}

Use the ternary operator to simplify.

$var = isset($_POST['hello']) ? 'exists' : 'error';
                 ^            ^     ^    ^     |
                 |           then   |   else   |
                 |                  |          |
          if post isset         $var=this   $var=this

Shorter, but harder to understand. This can not only be used on the variable $var like above, but can also be used on echo like below to check if the variable is false:

$isWinner = false;

// 输出 'you lose'
echo ($isWinner) ? 'You win!' : 'You lose';

// 同上
return ($isWinner) ? 'You win!' : 'You lose';

Why use them?

I find ternary arithmetic fascinating. Some developers want performance, but the ternary operator is nice, especially when combined with other features, such as PHP 5.4's latest short echos.

<?php 
    $array = array(0 => &#39;orange&#39;, 1 => &#39;multicoloured&#39;); 
?>

<p>
    <?php foreach ($array as $key => $value) { ?>
        <span><?=($value===&#39;multicoloured&#39;)?&#39;nonsense&#39;:&#39;pointless&#39;?></span>
    <?php } ?>
</p>

<!-- Outputs:
    <span>
        pointless
    </span>
    <span>
        nonsense
    </span> 
-->

A slight digression, in 'view/template' (note the MVC example), if you want to use some server-side logic, using the ternary operator or other short sentences will be the best way. "Other short sentences", like the following:

if ($isWinner) :
    // Show something cool
endif;

Note, I personally don't like such meaningless short sentences.

How fast is the ternary operator?

People love micro-optimization. This is also done. So it's important to know how much faster ternary operations are than regular if / else statements.

From the article, I learned that it is about 0.5ms faster. This is already much faster!

Wait, that’s not the case. This conclusion comes from repeatedly performing thousands of operations on a single line of code. So don't worry at all, it's pointless.

Unpractical ternary operator

The code should be:

• Easy to read
• Easy to understand
• Easy to modify

Obviously, this depends on the coding ability of the person reading the code and the ability to understand such issues. There is no problem with the previous simple example, but the following one is bad:

echo ($colour === 'red') ? "Omg we're going to die" :
     ($colour === 'blue' ? "Ah sunshine and daisies" :
     ($colour === 'green' ? "Trees are green"
     : "The bloody colour is orange, isn't it? That was pointless."));

The reasons are as follows:

• Ternary nesting is too long
• You can use the switch statement
• The first one should be orange

##Summary

Ternary arithmetic is actually very simple, so there is no need to be afraid. Don't think there's any

speed increase, there's really no difference. Use it when you can make the result simple, look good, and always keep the code readable. Do not use the ternary operator without a ternary. Recommended learning: "

PHP Video Tutorial

"

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