Nullable types: better way to check for null or zero in c#

I'm working on a project where i find i'm checking for the following in many, many places:

if(item.Rate == 0 || item.Rate == null) { }

more as a curiousity than anything, what's the best way to check for both cases?

I've added a helper method which is:

public static bool nz(object obj)
{
    var parsedInt = 0;
    var parsed = int.TryParse(obj.ToString(), out parsedInt);
    return IsNull(obj) || (parsed && parsedInt == 0);
}

Is there a better way?

I like if ((item.Rate ?? 0) == 0) { }

Update 1:

You could also define an extension method like:

public static bool IsNullOrValue(this double? value, double valueToCheck)
{
    return (value??valueToCheck) == valueToCheck;
}

And use it like this:

if(item.IsNullOrValue(0)){} // but you don't get much from it

Although I quite like the accepted answer, I think that, for completeness, this option should be mentioned as well:

if (item.Rate.GetValueOrDefault() == 0) { }

This solution

does not require an additional method,
is faster than all the other options, since GetValueOrDefault is a single field read operation¹ and
reads easier than ((item.Rate ?? 0) == 0) (this might be a matter of taste, though).

¹ This should not influence your decision, though, since these kinds of micro-optimization are unlikely to make any difference.

Using generics:

static bool IsNullOrDefault<T>(T value)
{
    return object.Equals(value, default(T));
}

//...
double d = 0;
IsNullOrDefault(d); // true
MyClass c = null;
IsNullOrDefault(c); // true

If T it's a reference type, value will be compared with null ( default(T) ), otherwise, if T is a value type, let's say double, default(t) is 0d, for bool is false, for char is '\0' and so on...

Nullable types: better way to check for null or zero in c#

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