JSON to C# : convert an arraylist of doubles to an array of ints ?

Answer 1

Linq:

var array = (from double d in list
             select (int)d).ToArray();

Answer 2

I would think something like this (with converter):

    private void Main()
    {
        List<Double> lstd = new List<Double>();

        lstd.Add(100.0);
        lstd.Add(244.0);
        lstd.Add(123.0);
        lstd.Add(999.0);

        List<int> lsti = lstd.ConvertAll(new Converter<double, int>(DoubleToInt));

    }


    public static int DoubleToInt(double dbl)
    {
        return (int)dbl;
    }

Answer 3

If you want a sample of a working solution using ConvertAll, here's a quick snippet.

 public static void testCOnvertAll()
        {
            List<double> target = new List<double>();
            target.Add(2.3);
            target.Add(2.4);
            target.Add(3.2);

            List<int> result = target.ConvertAll<int>(new Converter<double, int>(DoubleToInt));

        }

        public static int DoubleToInt(double toConvert)
        {
            return Convert.ToInt32(toConvert);
        }

Answer 4

You need to be careful with ArrayLists because of boxing. Thus:

// list is ArrayList      
int[] array = Array.ConvertAll(list.ToArray(), o => (int)(double)o);

Note the cast is framed as (int)(double). This first unboxes the boxed double and then casts to an int.

To do this in older versions of .NET

// list is ArrayList
int[] array = Array.ConvertAll(
    list.ToArray(),
    delegate(object o) { return (int)(double)o; }
);

An alternative is

// list is ArrayList
int[] array = Array.ConvertAll(
    (double[])list.ToArray(typeof(double)),
    o => (int)o
);

Here we do not need an unboxing operation because we have first converted the ArrayList to an array of unboxed doubles.

To do this in older versions of .NET

// list is ArrayList
int[] array = Array.ConvertAll(
    (double[])list.ToArray(typeof(double)),
    delegate(double o) { return (int)o; }
);

Answer 5

The linq options are cleaner, but if you don't have linq.

//Assuming someValues is your input array and you're sure you don't need to check the types
int[] outputValues = new int[someValues.Count];
for (int i = 0; i < someValues.Count; i++)
   outputValues[i] = (int)someValues[i];