How to compare nullable types?
I have a few places where I need to compare 2 (nullable) values, to see if they're the same.
I think there should be something in the framework to support this, but can't find anything, so instead have the following:
public static bool IsDifferentTo(this bool? x, bool? y)
{
return (x.HasValue != y.HasValue) ? true : x.HasValue && x.Value != y.Value;
}
Then, within code I have if (x.IsDifferentTo(y)) ...
I then have similar methods for nullable ints, nullable doubles etc.
Is there not an easier way to see if two nullable types are the same?
Update:
Turns out that the reason this method existed was because the code has been converted from VB.Net, where Nothing = Nothing returns false (compare to C# where null == null returns true). The VB.Net code should have used .Equals... instead.
C# supports "lifted" operators, so if the type (bool? in this case) is known at compile you should just be able to use:
return x != y;
If you need generics, then EqualityComparer<T>.Default is your friend:
return !EqualityComparer<T>.Default.Equals(x,y);
Note, however, that both of these approaches use the "null == null" approach (contrast to ANSI SQL). If you need "null != null" then you'll have to test that separately:
return x == null || x != y;
if (x.Equals(y))
T? is NOT a reference type, it's a System.Nullable<T>. And this is a struct, so: a value type. Muhammad's code is perfectly legal and won't throw a NullReferenceException if x is null.
Use Compare:
http://msdn.microsoft.com/en-us/library/dxxt7t2a.aspx
Just use ==, or .Equals().
I wanted to find how to compare two nullable int on C#, but I always get this link after search, so if someone needs to compare exactly two nullable int, then this can be helpful
a.GetValueOrDefault(int.MinValue).CompareTo(b.GetValueOrDefault(long.MinValue));
(x?? 0).Equals(y)
will handle null as well as equals.
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x.Equals(y)andx == ywork just fine when x and/or y are instances ofNullable<T>. How is the linked method different? When should it be used?Nullabe.Compare<T>if you are looking for anIComparable<T>impl