What does this syntax ( page = $page ? $page : 'default' ) in PHP mean?

Question

I'm new to PHP. I came across this syntax in WordPress. What does the last line of that code do?

$page = $_SERVER['REQUEST_URI'];
$page = str_replace("/","",$page);
$page = str_replace(".php","",$page);
$page = $page ? $page : 'default'

Clerical

wow! overwhelming responses.. :) thanks – Clerical

possible duplicate of Reference - What does this symbol mean in PHP? – Hale

Answer 1

It's an example of the conditional operator in PHP.

It's the shorthand version of:

if (something is true ) {
    Do this
}
else {
    Do that
}

See Using If/Else Ternary Operators http://php.net/manual/en/language.operators.comparison.php.

Emia

Answer 2

That's the ternary operator:

That line translates to

if ($page)
    $page = $page;
else
    $page = 'default';

Averir

What do you mean by "the conditional operator". Don't you mean "the ternary operator" (one of the conditional operators)? – Chuppah

I wrote "ternary operator" originally. @Biles edited it and changed it to "conditional". Curious. – Averir

"the ternary operator" is ambiguous because there can be more than one. – Biles

The docs seem to disagree: "Another conditional operator is the "?:" (or ternary) operator." – Averir

Answer 3

It's a ternary operation which is not PHP or WordPress specific, it exists in most langauges.

(condition) ? true_case : false_case 

So in this case the value of $page will be "default", when $page is something similar to false — otherwise it will remain unchanged.

Dede

Answer 4

It means that if $page does not have a value (or it is zero), set it to 'default'.

Algonquian

Answer 5

More verbose syntax of the last line is:

if ($page)
{
    $page = $page;
}
else
{
    $page = 'default';
}

Inquisition

Answer 6

It means if the $page variable is not empty then assign the $page variable on the last line that variable or set it to 'default' page name.

It is called conditional operator

Xanthophyll

It's misnamed the ternary operator where it really is just a ternary operater. Granted that in most language it is the only ternary operator implemented but that doesn't preclude the creation of other operators that takes 3 arguments. A language could for example have an operator for declaring functions, much like Forth's : operator, that operates on function name, parameter list and code block. That would also be a ternary operator. – Boatel

"Conditional operator"? Don't you mean "ternary operator"? – Chuppah

Answer 7

That's the so-called conditional operator. It functions like an if-else statement, so

$page = $page ? $page : 'default';

does the same as

if($page)
{
    $page = $page;
}
else
{
    $page = 'default';
}

Georgettegeorgi

The reference says it is the ternary operator (or a ternary operator?), one of the conditional operators. Can you elaborate? – Chuppah