[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]
		[clear]

//notes on warning problem //isset($lookup_table[$key]) will return false if $lookup_table[$key] is null ... //array_key_exists() will return true if the key exists but its value is null. // If key exists, return value, otherwise return null. //$a=array("Volvo"=>"XC90","BMW"=>"X5"); //if (array_key_exists("Volvo",$a)) //it is common to check for something's existence, and if it does'nt exist, use a default value. //The coalesce, or ??, operator is added, which returns the result of its first operand if it exists and is not NULL, or else its second operand. //$_GET['mykey'] ?? "" will not raise an E_NOTICE //$username = $_GET['user'] ?? 'nobody'; // equivalent to: $username = isset($_GET['user']) ? $_GET['user'] : 'nobody'; // variable $color is "red" if $color does not exist or is null // echo $color = $color ?? "red";