parameters in this function call are not understood

Question

This function is supposed to take two parameters, however there are characters included that I do not understand what they mean. What is the value of "?". What are the two parameters in this function, I know panel.id is one of them . any link to a library that explain them well ? thank you

setPanelType(panel.id, ((encType) ? PANEL_ST_ENC : PANEL_NORMAL))

The duplicate question posted here might be explaining what the "?" operator is. However I was not sure if it is used differently in a function parameter call. This question is not a duplicate of any.

`... ? ... : ...` is called the [Conditional (ternary) Operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator) — Andreas, Jan 21 '15 at 18:50
I assume this code is in Java, or in JavaScript. It would be best to only tag the language it's actually in. (Java != JavaScript) — T.J. Crowder, Jan 21 '15 at 18:56
Side note: All of the parentheses in that code other than the outermost ones are completely unnecessary (Java or JavaScript, or just about any other language syntactically derived from B). E.g., `setPanelType(panel.id, encType ? PANEL_ST_ENC : PANEL_NORMAL)` would be fine. — T.J. Crowder, Jan 21 '15 at 18:57
The project I am working on has both javascript and java code implemented. I to be honest was not sure this code lands to which language. — Mozein, Jan 22 '15 at 16:20

score 3 · Accepted Answer · edited Jan 21 '15 at 19:07

You've run in to something called the "conditional operator"*. It's basically a short way of writing an if-statement.

For example:

String var;
var = 1 > 0 ? "It's bigger than 0" : "It's 0 or smaller";

Is the same as:

String var;
if(1 > 0){
    var = "It's bigger than 0";
}else{
    var = "It's 0 or smaller";
}

* It's also sometimes called the "ternary" operator, but that's not quite correct. It's a "ternary operator" (an operator that accepts three operands, just like the multiplication operator * is a binary operator because it accepts two operands), but in theory there could be others. In fact, I think it's the only ternary operator in Java or JavaScript (at least for now).

Kudo's to T.J. Crowder for addition(s). – Bono Jan 21 '15 at 19:09 — Bono, Jan 21 '15 at 19:09

score 0 · Answer 2 · edited May 23 '17 at 11:52

0

This syntax is shorthand for a conditional action in Javascript.

(condition) ? (true action) : (false action)

Related: JavaScript ternary operator example with functions

edited May 23 '17 at 11:52

Community

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answered Jan 21 '15 at 18:50

Blake Frederick

1,510
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Replace "action" with "expression". – laune Jan 21 '15 at 18:50

score 0 · Answer 3 · answered Jan 21 '15 at 19:00

The '?' means Ternary Operator as said above, encType is a boolean variable.

setPanelType(panel.id, ((encType) ? PANEL_ST_ENC : PANEL_NORMAL))

is equals to:

if (encType)
   setPanelType(panel.id, PANEL_ST_ENC))
else 
  setPanelType(panel.id, PANEL_NORMAL))

parameters in this function call are not understood

3 Answers3