在多个值上使用布尔运算符的快捷方式

Question

First off, sorry if the title isn't clear or descriptive; I didn't know what to write exactly.

I'm wondering if there is a better way to do this operation:

bool result = variable1.innerValue.level2.innerValue == 1 || 
              variable1.innerValue.level2.innerValue == 2 || 
              variable1.innerValue.level2.innerValue == 3;

We can't write something like:

bool result = variable1.innerValue.level2.innerValue == (1 || 2 || 3);

This will give a syntax error.

Any ideas?

Answer 1

You could use a collection as placeholder and Enumerable.Contains :

if(new[]{1, 2, 3}.Contains(variable1.innerValue.level2.innerValue))
{

}

or, for what it's worth, this extension:

public static bool In<T>(this T source, params T[] list)
{
  if(null==source) throw new ArgumentNullException("source");
  return list.Contains(source);
}

which enables you to write this:

if(variable1.innerValue.level2.innerValue.In(1, 2, 3))
{

}

What are your favorite extension methods for C#? (codeplex.com/extensionoverflow)

Answer 2

In this case. you can do Enumerable.Range(1, 3).Contains(variable1.innerValue.level2.innerValue) .

Answer 3

using System.Linq;
...
bool result = new[] {1, 2, 3}.Contains(variable1.innerValue.level2.innerValue);

Answer 4

var listToCheck = new int[]{1,2,3};
var innerValue = variable1.innerValue.level2.innerValue;

bool result = listToCheck.Contains(innerValue);

Answer 5

Honestly, the first thing that comes to my mind is the good old Introduce Explaining Variable refactoring, which not only reduces the duplication but also makes your code more self-explanatory:

var innerValue = variable1.innerValue.level2.innerValue;
bool result = innerValue == 1 || innerValue == 2 || innerValue == 3;

Answer 6

怎么样

(new List<int>(){1,2,3}).Exists(i=>i == variable1.innerValue.level2.innerValue)