Of course a switch statement would be still yet cleaner ...

I hate those if-else statements.
I would prefer switch statement if I can, otherwise use a Dictionary.

Something like

public int GetNumberFromToken(string token)
{
const int defaultTokenNumber = 20;

Dictionary<string, int> tokenToNumberMap = new Dictionary<string, int>();
tokenToNumberMap.Add("A", 1);
tokenToNumberMap.Add("B", 4);
tokenToNumberMap.Add("C", 5);
tokenToNumberMap.Add("X", 10);

return tokenToNumberMap.ContainsKey(token) ? tokenToNumberMap[token] : defaultTokenNumber;
}

JD

That is way cleaner. So basically you're just chaining ternary operators together? Reminds me of the syntax in F# a little bit.

I dont mean to hate but I can not believe that this made it to dzone. What were people smoking when they kicked this up? I HATE ternary operators because in the real world most of the code you see is like the snippet second commentator posted. Every decent programmer knows about these ternary crappy operator but tends to not use them because they get confusing!

i'll stick with the traditional if, else which is more legible or switch statements in the case that you've presented.

Chaining If/else statements is something that u learn is a no no after programming for a couple years. First, C# can optimize switch statements making them more efficient (not always the best choice, but in ur example that is clearly better)

If ur more than a "faint of heart" programmer. This should be in the Strategy Design pattern. Yeah it increases the code a bit (like most design patterns) however once that method passes your TDD tests the beauty is that it never gets touched again as the method/classes are not coupled.

Bart, you could not use a switch statement in this case because the strings that the variable is being compared to are not constants.

Of course if you use Magical Number and magical letters, it seems easier that way.

However, I agree with JD.

Please use Dictionary. For god sake, put those letters in a configuration somewhere and add them to a dictionary. Even better, build a section in your Web.Config (or App.Config) that contains those value and dynamically load them into a dictionary at load time. No more "if" loop.

Using already existing structure is a best practice.

Well, for dictionaries, it's a bit of a mixed bag.

The example posted by JD is just scary bad. Building an entire dictionary just to locate one value? That's going to run SEVERAL orders of magnitude slower that any other version here. Remember, the the advantage of a dictionary is that is finds items in O(ln N) time. But building a dictionary is necessarily an O(N) operation.

Now, if we had a large number of values to test (10 to 20 at least), AND we could build the dictionary once per session (easy in Winforms; a bit trickier in WebForms) then using a dictionary is the best option.

I wouldn't necessarily put the values in a app/web.config. Basically, if there are enough values for a dictionary, then there are probably too many for an app.config. They probably should be read from a database. Also, remember that a magic number is a magic number no matter where it is. If either side of the mapping is an enum (usually a very good bet), then the mapping must be done in code. If you try putting enum values in the app.config, there it's the one with magic numbers.

I like the idea of using a dictionary or strategy pattern, but isn't there some way we can shoe-horn a fricken XML config file into this 5 lines of code? Could maybe dependency injection be used? Or a web service? Here's hoping.

Oops sorry, I wasnt parodying the immediately preceding comment there - I hadnt noticed it. Serendipity!

Great way to confuse junior members of the team.

The ternary operator has always been a cryptic construct that has been met with much controversy. I prefer the more verbose form, as junior members and non-coding parties have a higher chance of understanding the code quickly.

I am really not so concerned with "programming efficiency" from a keystroke standpoint, or from a "oh I saved 5 lines of IL with this method" standpoint either. Obviously if something is going to be looped over it must be efficient, however. "source code efficiency" at the price of legibility only leads to higher lifetime support costs, either in bugs that need to be fixed, or time wasted by people trying to figure out clever code.

Legibility prevents bugs, and I find bugs far more troubling than taking up an extra 5 lines of code by doing something verbosely.

The compiler has your back on this one.

I think the example is pretty neat. Obviously not for every situation. I agree with the comment further above, the Dictionary is maybe overkill for such a short list, but good idea for longer stuff.
I think even somebody that has no idea about the ternary operators can understand the example.

Although most of us are C# developers, VB.NET has their "Tertiary" operator as well called IIF. However, IIF doesn't work the way a C/C++/C# dev would expect. VB.NET will actually interpret all three statements, the validation, the true condition, and the false condition, regardless of True or False. This is particularly nasty if you're inlining a If-Not-Null check (Common in DB Access/Mapping code).

Just a heads up.

I don't like the 'else if' constructs either. Any modification of a single statement in such a chain may affect all the following statements. Also, when inspecting such code, one has to go through all the statements or risks missing an important detail.

In simple cases the switch statement solves the problem.

For more complex cases I wish to suggest the following construct:
int a = 3;

for ( ;; )
{
if ( a < 2 )
{
Console.WriteLine( a );
break;
}

if ( a >= 2 && a < 5 )
{
Console.WriteLine( a ); // this will be executed
break;
}

if ( a >= 5 )
{
Console.WriteLine( a );
break;
}

} // for

It involves a bit more code, of course, but is more clear and robust, IMHO.

WTF?

I have been programming for more than 2 decades and I have never seen the ternary operator abused in such a heinous manner!

You are the weakest link, good-bye!

Code looks good and understable.Best utilization of ternary operator.


public class test1 {

/**
* @param args
*/
public static void main(String[] args) {
int iInt = 13;
int iJ = (iInt == 10) ? 10
: (iInt == 20) ? 20
: (iInt == 30) ? 30
:40;
System.out.print(iJ);
}

for similar code simple and nice. Why don't use it?

Philippe, thanks for a nice little construct.
I can't wait to have the opportunity to use it!

This reminds me of other things which at first
glance look cryptic but at second glance look
beautiful while still being simple.

e.g. ZoneLayout, Stripes & XStream