1 . Which security protocol or measure would provide the greatest protection for a wireless LAN? WPA2 cloaking SSIDs shared WEP key MAC address filtering 2 . Refer to the exhibit. All trunk links are operational and all VLANs are allowed on all trunk links. An ARP request is sent by computer 5. Which device or devices will receive this message? only computer 4 computer 3 and RTR-A computer 4 and RTR-A computer 1, computer 2, computer 4, and RTR-A computer 1, computer 2, computer 3, computer 4, and RTR-A all of the computers and the router 3 . Refer to the exhibit. Hosts A and B, connected to hub HB1, attempt to transmit a frame at the same time but a collision occurs. Which hosts will receive the collision jamming signal? only hosts A and B only hosts A, B, and C only hosts A, B, C, and D only hosts A, B, C, and E 4 . Refer to the exhibit. Router RA receives a packet with a source address of 192.168.1.65 and a destination address of 192.168.1.161...
This is the conditional operator.
ReplyDelete$x ? $y : $z
means "if $x is true, then use $y; otherwise use $z".
People will tell you that ?: is "the ternary operator". This is wrong. ?: is a ternary operator, which means that it has three operands. People wind up thinking its name is "the ternary operator" because it's often the only ternary operator a given language has.
It's called a ternary operator. If the first expression evaluates to true, HTTPS_SERVER is used, else HTTP_SERVER is chosen.
ReplyDeleteIt's basically a shorthand if statement, the above code could also be rewritten as follows:
if ($request_type == 'SSL') {
HTTPS_SERVER;
} else {
HTTP_SERVER;
}
This is sometimes known as the ternary conditional operator. Ternary means that it has three arguments, as x ? y : z. Basically, it checks if x is true; if it is, then put y instead of this operation, otherwise z.
ReplyDelete$hello = $something ? "Yes, it's true" : "No, it's false";
This is a short way of writting IF sentences. It is also used in other languages like Java, Javascript and others.
ReplyDeleteYour code:
$protocol = $request_type == 'SSL' ? HTTPS_SERVER : HTTP_SERVER;
can be written like this:
if($request_type == 'SSL')
$protocol = HTTPS_SERVER;
else
$protocol = HTTP_SERVER;
Conditional operator ?: is an operator which is used to check a condition and select a value depending on the value of the condition. It is expressed in the following form:
ReplyDeletevariable = condition ? expression1 : expression2;
It works as follows...
Firstly, condition is evaluated.
If the condition is true, then expression1 is evalauated. And the value of expression1 is assigned to the variable.
If the condition is false, then expression2 is evaluated. And the value of expression2 is assigned to the variable.
For example:
x = (a>b) ? 5 : 9
In this, for x, firstly the condition (a>b) is evaluated. If this condition becomes true, then x will become the value 5 (ie, x=5). But if the condition (a>b) becomes false, then x will attain the value 9 (ie, x=9).
Ternary Operator
Sometimes conditional operator ?: is also called a ternary operator. This is so because it involves three operands. For example:
x ? y : z
Here, x,y and z are the three operands. If condition x is true, then value y is assigned otherwise value z is assigned.
That's basically a fancy way if writing an if else statement.
ReplyDeleteSome say its easier to read, some say not.
ternary operator at wikipedia
As John T says, it is called a ternary operator and is essentially a shorthand version of an if /else statement. Your example, as a full if / else statement, would read;
ReplyDeleteif($request_type == 'SSL')
{
HTTPS_SERVER;
}
else
{
HTTP_SERVER;
}
That is a one line if statement:
ReplyDeletecondition ? true : false
Translated to an ordinary if statement in your case, that would be:
if($request_type == 'SSL') HTTPS_SERVER;
else HTTP_SERVER;