Multiple data type input in C# function

Question

I am switching from an Arduino (c language) to a Netduino (c# language).

In my arduino program I have the following function (built-in):

I would like to convert this to C#. I have the following code:

int ConstrainValue(int value, int min, int max)
    {
        int Value = value;
        int Min = min;
        int Max = max;

        if (Value >= Max)
        {
            Value = Max;
            return Value;
        }
        else if (Value <= Max)
        {
            Value = Min;
            return Value;
        }
        return Value;
    }

However, I would also like to be able to use this for the double datatype. Is it possible to modify the function so multiple datatypes can be used?

You will have to copy/paste a few overloads of this for different data types. The most practical solution. — Jon, Jan 28 '13 at 10:12
I think the second comparison should compare to `Min`, not `Max` again. Also in .NET value types are passed by value, not by reference, so you don't need to create the capitalized copies. — C.Evenhuis, Jan 28 '13 at 10:12
You could modify the method and use `double`s instead of `int`s. That way you won'z lose precicion... — Spontifixus, Jan 28 '13 at 10:13
@sll No, generics are not available in micro framework http://stackoverflow.com/questions/3327036/net-micro-framework-and-unsupported-features-what-is-the-impact — weston, Jan 30 '13 at 09:17

score 5 · Answer 1 · answered Jan 28 '13 at 10:12

5

It is, using IComparable.

static T ConstrainValue<T>(T value, T min, T max) where T : IComparable
{
    if (value.CompareTo(max) > 0)
        return max;
    else if (value.CompareTo(min) < 0)
        return min;
    return value;
}

answered Jan 28 '13 at 10:12

Cédric Bignon

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score 1 · Answer 2 · answered Jan 28 '13 at 10:11

1

Yes it is, you need to make it a generic function, something like that:

T ConstrainValue<T>(T value, T min, T max) where T : IComparable

I think you'll need to add some more interfaces though

answered Jan 28 '13 at 10:11

ppetrov

3,077
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But this would cause boxing for all numeric types. Not ideal. – Jon Jan 28 '13 at 10:12
@Jon Are you sure it won't just constraint the types you use at the build time? (I'm actually really asking, never thought that kind of implementation causes boxing...) – ppetrov Jan 28 '13 at 10:16
`CompareTo` takes an object - so you get boxing there. – weston Jan 28 '13 at 10:19
indeed, never thought about that, well I learned something today thx :) – ppetrov Jan 28 '13 at 10:20

weston · Answer 3 · 2013-01-28T10:30:27.977

1

By specifying struct, you will not get boxing when calling the method, but by using IComparable you will still get it when calling CompareTo because that interface method takes an object.

So use IComparable<T> and I'm pretty sure there's no boxing now:

    private static T ConstrainValue<T>(T value, T min, T max)
      where T : struct, IComparable<T>
    {
        if (value.CompareTo(max) > 0)
        {
            return max;
        }

        if (value.CompareTo(min) < 0)
        {
            return min;
        }

        return value;
    }

edited Jan 28 '13 at 10:30

answered Jan 28 '13 at 10:17

weston

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Thanks for the replies! However, I get the following error on IComparable: The non-generic type 'System.IComparable' cannot be used with type arguments. And on .CompareTo: 'T' does not contain a definition for 'CompareTo' and no extension method 'CompareTo' accepting a first argument of type 'T' could be found (are you missing a using directive or an assembly reference?) – JR_ Jan 29 '13 at 19:20
I dunno - there's nothing wrong with that code, and only using needed is `using System;`. But then you are using the .net micro framework, which may not have a generic `IComparable`. – weston Jan 30 '13 at 08:55
1

Indeed, generics are not available in micro framework http://stackoverflow.com/questions/3327036/net-micro-framework-and-unsupported-features-what-is-the-impact My answer will not work for you. – weston Jan 30 '13 at 09:15

score 0 · Answer 4 · answered Jan 28 '13 at 10:18

0

By using generics you can use multiple datatypes

T ConstrainValue(T value, T min, T max) where T : IComparable

answered Jan 28 '13 at 10:18

Lakshminarayana Medikonda

11
2
4

score 0 · Answer 5 · answered Jan 31 '13 at 16:09

.net micro (netduino) does NOT support generics as of v4.2.

You would have to use another scheme such as a function that takes objects as arguments and then does the work. You'll then have to use 'as' or casting on the return in the calling function:

    object ConstrainValueInt(object value, object min, object max)
        {
   /* this could still get you in trouble with bool type */
          if (value.GetType().isValueType && min.GetType().isValueType && max.GetType().isValueType )
          return ( (value >= max)? max : ((value <= min)? min : value));
        }

Multiple data type input in C# function

5 Answers5