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Shorthand C#

Posted on 2007-11-25
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Last Modified: 2013-11-07
I've seen this really funky shorthand code in a blog post that i now can't remember.  It's been bugging me for a while now so i thought i'd ask.

Currently i have this: string answer = (obj =! null)? obj: " ";
It's something similar to string answer = (obj : " ");

I know i could write a method to handle this but i'm looking for the inbuilt way.

Any ideas?  Thanks  Also, if you know of any other cool little short hand tricks feel free to post =)
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Question by:UnexplainedWays
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12 Comments
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 20348303
well, start with this:
     string answer = (obj =! null)? obj: " ";
it can't be =!, should be !=:
     string answer = (obj != null)? obj: " ";

also, if obj is not string type, will produce a compiler error, but can be solved as:
     string answer = (obj != null) ? obj.ToString() : " ";
0
 
LVL 12

Author Comment

by:UnexplainedWays
ID: 20348360
Yeah sorry it should lol, that's what happens when you quickly write up code in the box down the end of the page.

obj will be the same type as answer.
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20348371
so, my first post answers your question?
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LVL 12

Author Comment

by:UnexplainedWays
ID: 20348406
You fixed up the line that i used as an example of what i'm after, however i'm still looking for the shorter syntax.

what i'm after is something similar to this:  string answer = (obj : " ");
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20348429
no, there isn't shorter syntax than the ternary operator, assuming that 'obj' is string:
     string answer = (obj != null) ? obj : " ";

In C++ could be shorter, because null can be evaluate as a bool, something like:
    string answer = obj ? obj : " ";

But this is not possible with C#.
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LVL 12

Author Comment

by:UnexplainedWays
ID: 20348558
I've seen it before, it was in a blog and it was mentioned because no many people knew about it.

I know i wasn't dreaming.........
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 20348607
maybe some compiler's unexpected behaviour, not a correct use at all...
0
 
LVL 12

Author Comment

by:UnexplainedWays
ID: 20348612
I'm just anoyed i didn't save it.  I showed it to people @ work and no one else knew about it.
0
 
LVL 7

Accepted Solution

by:
photowhiz earned 2000 total points
ID: 20354779
You might be thinking of the coalesce operator on nullable value types:

    int? x = null;
    int y = x ?? 5;        // y is 5

This will not work with strings because strings are not value types.
0
 
LVL 12

Author Comment

by:UnexplainedWays
ID: 20354824
BINGO!!!!!!!!!!!!!!!!!!!!!!!!

I just tested it out and it works.
            string a = null;
            string b = "something";
            string c = (a ?? b);

Here's more about it if someone reads this page later: http://blog.benhall.me.uk/2007/10/c-null-coalescing-operator-and.html

I knew it was something close  answer = (obj : " ");  >>>>>> answer = (obj ?? " ");
0
 
LVL 7

Expert Comment

by:photowhiz
ID: 20360365
You're right, it does work on strings.

Ya learn something every day.
0
 

Expert Comment

by:Siconltd
ID: 26172622
If you are reverring to c# shorthand then there are a couple of things i know...

1.  if ? else : then

eg,  bool AIsMoreThanTen =  (a > 10) ? true : false

the value before the question mark must equate to a bool, the value on the left of the colon is the 'then' and the right of the colon is the else and either the then or the else value is returned, the return values do not have to be a bool, only the value to the left of the question mark needs to be a bool

2.  

public string TestItem
{
get
{
return Session["TestItem"] as string ?? "Test Item"
}

The ?? operator checks if the value on the left is null, if it is, it returns the value on the right
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