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if (nThatVeryLongVariableYourMateNamed.Excludes(0,1,2))

int n = nThatVeryLongVariableYourMateNamed;
if (n == 0 || n == 1 || n == 2)
{
}

switch(nThatVeryLongVariableYourMateNamed)
{
  case 0:
  case 1
  case 2
    break;
}

private static readonly HashSet<int> validValues = new HashSet<int> { 0, 1, 2};
.
.
.
if (validValues.Contains(nThatVeryLongVariableYourMateNamed))
{
}

if (new int[] { 0, 1, 2}.Contains(nThatVeryLongVariableYourMateNamed))
{
}

Result: Integer;
...
if aPrompt and not (Result in [0, 1, 2, 4]) then
...

static class Extensions
{

    public static bool In<T>(this T item, params T[] items)
    {
        if (items == null)
            throw new ArgumentNullException("items");

        return items.Contains(item);
    }

}

class Program
{

    static void Main()
    {

        int myValue = 1;

        if (myValue.In(1, 2, 3))
            // Do Somthing...

        string ds = "Bob";

        if (ds.In("andy", "joel", "matt")) 
        // Do Someting...
    }
}

public static class SomeExtensions
{
    public static bool IsOneOf<T>(this T value, params T[] options)
    {
        if (options is null || options.Length == 0) return false;
        return Array.IndexOf(options, value) != -1;
    }
    
    public static bool IsNotOneOf<T>(this T value, params T[] options)
    {
        if (options is null || options.Length == 0) return true;
        return Array.IndexOf(options, value) == -1;
    }
}

...

if (nThatVeryLongVariableYourMateNamed.IsNotOneOf(0, 1, 2))

bool contains(int var, std::vector<int> ints) {
   for (int x :ints) if (var == x) return true;
   return false;
   }

...

   int veryLongVarName = 12;
   if (contains(veryLongVarName, { 1, 2, 3 })) {
      OutputDebugString(L"Matches! Now we have fire!");
      }

{
  int localVLVYMN = thatVeryLongVariableYourMateNamed;
}

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

{
    ref int localVLVYMN = ref thatVeryLongVariableYourMateNamed;
    ...
}

Richard Deeming wrote:

Now any changes to your alias will be reflected in the original.

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

if nThatVeryLongVariableYourMateNamed not in [0,1,2]:

if nThatVeryLongVariableYourMateNamed not in range(3):

if nThatVeryLongVariableYourMateNamed not in range(0,3):

if nThatVeryLongVariableYourMateNamed not in range(0,3,1):