[SOLVED] "? :" What does it mean?

[Maq]

I've been teaching myself PHP and have seen people using the syntax, "? :".  I assume it is an alternative for a condition statement but I have been searching Google and can't find an explanation. 

 

Example:

$port = ($port) ? ':'.$_SERVER["SERVER_PORT"] : '';

 

Please explain.

[effigy]

Ternary Operator

[Maq]

This syntax is not listed in the link provided but I know what it means now.  In the example that I gave it means:

 

If there is a port $port = $_SERVER["SERVER_PORT"];

 

If there isn't a port then $port = '';

 

Correct me if I'm wrong but, this is just a shortcut for IF/ELSE statement.

 

Thanks

[lanmonkey]

yes

[effigy]

This syntax is not listed in the link provided

 

From the link:

 

The expression (expr1) ? (expr2) : (expr3)  evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.

[Mchl]

 

Correct me if I'm wrong but, this is just a shortcut for IF/ELSE statement.

 

 

Not really but works in similar way.

 

You can't do

 

(mysql_connect($a,%b,$c,$d)) ? {$query = "query"; mysql_query($query); etc..} : {echo mysql_error();}

 

Ternary operator is best used, where you want to assign a value to a variable according to some condition.

For example

 

echo ($mysql_query("INSERT INTO ...")) ? "Data saved" : "Error: ".mysql_error();

[effigy]

You can't do

 

(mysql_connect($a,%b,$c,$d)) ? {$query = "query"; mysql_query($query); etc..} : {echo mysql_error();}

 

Because, per the documentation, those are not valid expressions. $query = "query" && mysql_query($query) might work, but then you're entering into a realm of sloppy code.

[Mchl]

There was this contest for worst code... let me see if I saved the url....

[Maq]

Hey sorry effigy, I only looked at the Comparison Operators table (obviously) and didn't think it was there.

 

Ternary operator is best used, where you want to assign a value to a variable according to some condition.

 

I see what you mean Mchl.  Just like in my example, you're assigning port to the SERVER_PORT if it exists but if not then assign nothing.

[The Little Guy]

$a = 1;
if($a == 1){
     echo 'a is one!'
}else{
     echo 'a is not one ';
}

// Is the same as:

$a = 1;
echo ($a == 1)? 'a is one!' : 'a is not one ';

[Maq]

Thanks The Little Guy.  This, yet again, confirms the concept of the ?: ternary operator for me.  Is there a name for this type of ternary operation?