What are the PHP operators “?” and “:” called and what do they do?

Question

What are the ? and : operators in PHP?

For example:

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

Answer 1

It's called a ternary operator. If the first expression evaluates to true, HTTPS_SERVER is used, else HTTP_SERVER is chosen.

It's basically a shorthand if statement, and the above code could also be rewritten as follows:

if ($request_type == 'SSL') {
   HTTPS_SERVER;
}
else {
   HTTP_SERVER;
}

Answer 2

This is a short way of writing if sentences. It is also used in other languages like Java, JavaScript and others.

Your code,

$protocol = $request_type == 'SSL' ? HTTPS_SERVER : HTTP_SERVER;

can be written like this:

if ($request_type == 'SSL')
    $protocol = HTTPS_SERVER;
else
    $protocol = HTTP_SERVER;

Answer 3

Conditional operator ? : is an operator which is used to check a condition and select a value depending on the value of the condition. It is expressed in the following form:

variable = condition ? expression1 : expression2;

It works as follows...

1. Firstly, condition is evaluated.
2. If the condition is true, then expression1 is evalauated. And the value of expression1 is assigned to the variable.
3. If the condition is false, then expression2 is evaluated. And the value of expression2 is assigned to the variable.

For example:

x = (a>b) ? 5 : 9

In this, for x, firstly the condition (a>b) is evaluated. If this condition becomes true, then x will become the value 5 (ie, x=5). But if the condition (a>b) becomes false, then x will attain the value 9 (ie, x=9).

Ternary Operator

Sometimes conditional operator ? : is also called a ternary operator. This is so because it involves three operands. For example:

x ? y : z

Here, x,y and z are the three operands. If condition x is true, then value y is assigned otherwise value z is assigned.

Answer 4

This is the conditional operator.

$x ? $y : $z

means "if $x is true, then use $y; otherwise use $z".

It also has a short form.

$x ?: $z

means "if $x is true, then use $x; otherwise use $z".

People will tell you that ?: is "the ternary operator". This is wrong. ?: is a ternary operator, which means that it has three operands. People wind up thinking its name is "the ternary operator" because it's often the only ternary operator a given language has.

Answer 5

As John T says, it is called a ternary operator and is essentially a shorthand version of an if /else statement. Your example, as a full if / else statement, would read;

if($request_type == 'SSL')
{
    HTTPS_SERVER;
}
else
{
    HTTP_SERVER;
}

Answer 6

That's basically a fancy way of writing an if-else statement. Some say it's easier to read, some say not.

Ternary operator at Wikipedia