The default for KeyValuePair

Question

I have an object of the type IEnumerable> keyValueList, I am using

 var getResult= keyValueList.SingleOrDefault()         


        

Answer 1

You can create a general (and generic) extension method, like this one:

public static class Extensions
{
    public static bool IsDefault(this T value) where T : struct
    {
        bool isDefault = value.Equals(default(T));

        return isDefault;
    }
}

Usage:

// We have to set explicit default value '0' to avoid build error:
// Use of unassigned local variable 'intValue'
int intValue = 0;
long longValue = 12;
KeyValuePair kvp1 = new KeyValuePair("string", 11);
KeyValuePair kvp2 = new KeyValuePair();
List> kvps = new List> { kvp1, kvp2 };
KeyValuePair kvp3 = kvps.FirstOrDefault(kvp => kvp.Value == 11);
KeyValuePair kvp4 = kvps.FirstOrDefault(kvp => kvp.Value == 15);

Console.WriteLine(intValue.IsDefault()); // results 'True'
Console.WriteLine(longValue.IsDefault()); // results 'False'
Console.WriteLine(kvp1.IsDefault()); // results 'False'
Console.WriteLine(kvp2.IsDefault()); // results 'True'
Console.WriteLine(kvp3.IsDefault()); // results 'False'
Console.WriteLine(kvp4.IsDefault()); // results 'True'