What is the meaning of the '?', '()', and ':' symbols in PHP?

Question

I\'ve finally remembered what to ask. I never really got what : and ? do when a variable is being defined like this:

$ip = ($_SERVER[\'HTTP_X_FORWARDED_FOR\'         


        

Answer 1

"?:" (or ternary) operator

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

See this example: