C#, “?” and “:” operators

I not found any solution for my problem so i ask, how ? and : operators works when i have multiple statemants?

?

:

What i want to do, i have pixel on the middle pixel[pos] and pixels around, its look like:

pixel[pos]

0 0 0
0 x 0
0 0 0


x is a center pixel.

x

Im checking, if i have any white (zero) pixel around it. If is anyone, i marked pixel as two. If not, so pattern looks like:

zero

two

1 1 1
1 x 1
1 1 1


1 is an black pixel, i set it to one.

1

one

Now, the code:

if(pixels[positionOfPixel] == one && x > 0 && x < width
&& y > 0 && y < height)

pixels[positionOfPixel] = pixels[positionOfPixel - 1] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel + 1] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel - offset] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel + offset] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel - offset + 1] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel + offset - 1] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel - offset - 1] == zero ? two :
pixels[positionOfPixel] = pixels[positionOfPixel - offset + 1] == zero ? two : zero;



My question is, why every one pixel is marked as two ? Why it didnt recognize pixel, where every pixel arond is one (like in second pattern)?

one

two

one

Thanks for any advices!

?:

a?b:c

if

1 Answer
1

I'm not a C# specialist, but there is common rule how ? : operator can be used.

x = (boolean condition) ? reult_if_true : result_if_false;


E.g.

drink = isThisPersonAGirl ? wine : beer;


If you want to use many conditions with ? : operator, you should do it that way:

x = (boolean condition 1) ? result_if_true : (boolean condition 2) ? result_if_bool_2_is_true : result_if false;


E.g.

drink = isThisPersonAChild ? lemonade : isThisPersonAGitl ? wine : beer


In your code snippet, it's hard to understand what's going on because you use = operator too often. In most languages, you could initalize several variables like this:

a = b = c = 0, so a, b, c will be = 0;

So I think your mistake is using = operator too often so maybe only this condition does matter, while others are simply skipped:

pixels[positionOfPixel - offset + 1] == zero ? two : zero;


Sorry of it doesn't help, since I'm really not a C# coder)

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