C# Generic Type Constraints
I have never used generics before and was wondering how to constrain the Type to either Double[]
or List<Double>
(or if this is even the correct thing to do). I need to c开发者_运维问答alculate the average of many numbers that are sometimes known in advance (i.e. I can create an array of exact size) but, at other times, are generated immediately before the calculation (i.e. I use a List).
I would like this generic method Average(T arrayOrList)
to be able to accept an array or list instead of overloading the Average()
method.
Thanks!
Since both double[]
and List<double>
implement IEnumerable<double>
, I'd suggest the following:
public double Average(IEnumerable<double> arrayOrList) {
// use foreach to loop through arrayOrList and calculate the average
}
That's simple subtype polymorphism, no generics required.
As others have already mentioned, if you simply want to calculate an average, such a method already exists in the framework.
I would just use IEnumerable<double>
, since all you need to do is loop over the data (and both lists and arrays support this, as do deferred sequences).
In fact, Microsoft got there first:
var avg = sequence.Average();
http://msdn.microsoft.com/en-us/library/bb358946.aspx
Why not just write a function that accepts an IEnumerable<double>
?
Then if you really want to use an ArrayList
, I assume not by choice you can use the AsEnumerable()
extensions.
EDIT, seems I miread ArrayOrList, but the answer still applies, although it was 56 secs late
var x = new List(); var average = x.Average(); var y = new Double[10]; var average = y.Average();
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