检查多个类似条件时，是否有办法使if语句更短且更好看？ （C＃）

Question

(not sure if title explains the matter well enough)

I have this piece of code:

string input = "5";
   if (input == ""  ||
       input == "1" ||
       input == "2" ||
       input == "3" ||
       input == "4" ||
       input == "_" ||
       input == "6" ||
       input == "7" ||
       input == "8")
     {/* ... */}
   else
     {/* ... */}

How can I make it look better? Is there some way to remove repeating input s?

upd : switch will probably make it even worse, because in my case I'm going to check for many conditions, most of which will run very limited number of methods.

Answer 1

Yes, you can write an extension method like this one:

    public static bool In<T>(this T value, params T[] list)
    {
        return list.Contains(value);
    }

And use it as follows:

if (input.In("", "1", "2", ...))
...

Answer 2

Well, you can use a switch in the general case (although that experience is much better in VB.NET) but if they're all going to be one character or less, you can use a string:

if("1234_678".Contains(input)) {
    // ...
}

Answer 3

Wrap the conditional expression in a function and code becomes easier to read. The actual expression isn't any simpler but the code is a bit easier to read.

if (IsSomething(input))
{
 /* do stuff */
}

Answer 4

Maybe you could try using a switch. Its probably more presentable. This would be more appropriate for individual tests if that is what you want.

More information can be found here: http://msdn.microsoft.com/en-us/library/06tc147t%28v=vs.71%29.aspx

    switch(input){
      case "1":
      // Do something
      break;
      case "2":
      // Do something else
      break;
      case "_":
      // Do something else
      break;
      default:
      // Otherwise do this
      break;
    }

Answer 5

Or you could do:

List<string> list = new List<string>{"","1","2","3","4","5","6","7","8"};

            if (list.Contains(input))
            {
                Console.WriteLine("found");
            }

Answer 6

This will be an option to solve this problem:

  string input = "5";
  List<string> Values = new List<string>{ "1", "2","3","4", "5" };
  if(Values .Contains(input))
    {
         //Your Action
    }