How to check if at least one enum value is equal to a variable within an if condition

Question

The common way of checking equality on multiple variables within an if condition is as following.

public enum Values
{
    Value1,
    Value2,
    Value3
}
void MethodName (Values randomValue )
{
 if (randomValue == Values.Value1|| randomValue == Values.Value2)
  {
       // code here
  }
}

Rather than having an OR condition, is there a better way of doing this ?

"common way of checking equality on multiple variables" is actually different - stackoverflow.com/questions/3907299/…... But you already should have found it before and disliked. For future questions please clarify your preference (otherwise it look like you have not done any research and ...) — Alexei Levenkov
– Alexei Levenkov, Commented May 31, 2016 at 3:34
Enums better to work in switch statements rather than if blocks. If you want to have multiple equality conditions, define logic for a main case and use goto case which point to main case for another related cases. — Tetsuya Yamamoto
– Tetsuya Yamamoto, Commented May 31, 2016 at 3:42

Community · Accepted Answer · 2017-05-23 12:31:35Z

11

A few options:

You can define your enums as flags. This means each value must be a power of 2 (1, 2, 4, 8, etc). Then, you could write:

if (randomValue & (Values.Value1 | Values.Value2) > 0)
{
     //...
}

You can use a switch

switch (randomValue)
{
    case Values.Value1:
    case Values.Value2:
    {
        //Do something
        break;
    }
    case Values.Value3:
        //Do something else
        break;
    default:
        break;
}

You can use an array (nicer if you have predefined sets of values you want to search for).

if (new[] { Values.Value1, Values.Value2 }.Contains(randomValue))
{
}

or

static(?) readonly Values[] allowedValues = new[] { Values.Value1, Values.Value2 };

void MethodName(Values randomValue)
{
    if (allowedValues.Contains(randomValue))
    {
        //...
    }
}

edited May 23, 2017 at 12:31

CommunityBot

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answered May 31, 2016 at 3:26

Rob♦

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3 Comments

Jane Over a year ago

how about the other way around, sounds like the question could be "How to check if a value of a variable is defined as an enum value?" and then do if (Enum.IsDefined(typeOf(YourEnum, YourValue) { }? works for me :)

Jane Over a year ago

I do like the bitwise discussion in the flags post, thanks for posting!

Rob Over a year ago

@JanneAndersson That won't work for their given example, though, which is checking if it's Value1, Value2, but not Value3

Fredrik Karlsson Peraldi · Accepted Answer · 2018-02-22 02:28:29Z

By using Enum Flags we can do comparisons as follows:

[Flags]
public enum Values
{
  Value1 = 1 << 0,
  Value2 = 1 << 1,
  Value3 = 1 << 2
}

void MethodName(Values randomValue)
{
  if ((randomValue & (Values.Value1 | Values.Value2)) != 0)
  {
    // code here
  }
}

Note the Flags attribute and the bit shifting required for the Enum values. The Enum values can also be defined as:

  [Flags]
  public enum Values
  {
    Value1 = 1,
    Value2 = 2,
    Value3 = 4
  }

We can now parameterize the Allowed Values as follows:

      [Flags]
      public enum Values
      {
        Value1 = 1 << 0,
        Value2 = 1 << 1,
        Value3 = 1 << 2
      }    

      void MethodName(Values randomValue)
      {
        if (IsValid(randomValue, Values.Value1 | Values.Value2))
        {
          // code here
        }
      }

      bool IsValid(Values randomValue, Values allowedValues)
      {
        return ((randomValue & (allowedValues)) != 0);
      }

RISHABHA SINGH · Accepted Answer · 2016-05-31 03:36:22Z

-2

See this example

public enum Level {

HIGH,
MEDIUM,
LOW

}

You can refer to the constants in the enum above like this:

Level level = Level.HIGH;

Level level = ... //assign some Level constant to it

if( level == Level.HIGH) {

} else if( level == Level.MEDIUM) {

} else if( level == Level.LOW) {

}

answered May 31, 2016 at 3:36

RISHABHA SINGH

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1 Comment

Alexei Levenkov Over a year ago

Not clear how this code simplifies multiple conditions check.

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