Converting int[] to int?[]

Question

Hi

I am trying to fix an application where a method signature in a dependent dll changed its type from int[] to int?[].  Is there a clean way to change this? 

for example.  I have an Int32[] parameter passed in called ordernumbers

It would appear that if I did this:

System.Collections.Generic.List<int?> list = new System.Collections.Generic.List<int?>();

for(int=0;i<ordernumbers.length; i++)

{

list.Add(ordernumbers[i]);

}

int?[] convertedList = list.ToArray();

this should work.  I would then pass this to the underlying method that now requires an int?[] whereas before it was an int[].  I would think that there should be an easier/more terse way to do this.  I have a number of these to convert.

Thanks









Answer 1

Here are a couple useful methods I have and you can modify

//Convert any list object to a datatable
        public DataTable ConvertToDataTable<T>(IList<T> data)
        {
            PropertyDescriptorCollection properties =
               TypeDescriptor.GetProperties(typeof(T));
            DataTable table = new DataTable();
            foreach (PropertyDescriptor prop in properties)
                table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
            foreach (T item in data)
            {
                DataRow row = table.NewRow();
                foreach (PropertyDescriptor prop in properties)
                    row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
                table.Rows.Add(row);
            }
            return table;
        }
        public static DataSet ConvertToDataSet<T>(IList<T> list)
        {
            Type elementType = typeof(T);
            DataSet ds = new DataSet();
            DataTable t = new DataTable();
            ds.Tables.Add(t);
            //add a column to table for each public property on T
            foreach (var propInfo in elementType.GetProperties())
            {
                //t.Columns.Add(propInfo.Name, propInfo.PropertyType);
                Type ColType = Nullable.GetUnderlyingType(propInfo.PropertyType) ?? propInfo.PropertyType;
                t.Columns.Add(propInfo.Name, ColType);
            }
            //go through each property on T and add each value to the table
            foreach (T item in list)
            {
                DataRow row = t.NewRow();
                foreach (var propInfo in elementType.GetProperties())
                {
                    //row[propInfo.Name] = propInfo.GetValue(item, null);
                    row[propInfo.Name] = propInfo.GetValue(item, null) ?? DBNull.Value;
                }
                t.Rows.Add(row);
            }
            return ds;
        }

Edit: I ran this code and note what you need to do

int?[] testnullar = { null, 1, 3, 4 };
var testnullar2 = testnullar.ToArray();
int?[] testnullar3 = null;
//If you don't check for null conversion will have an exception
if (testnullar3 != null)
{
    var testnular4 = testnullar3.ToArray();
}

Answer 2

Hi Cheese,

what about using a LINQ-statement. :-)

int[] yourIntArray = new int[] { 1, 2, 3 };
int?[] converted = yourIntArray.Select(i => (int?)i).ToArray();

---

Thomas Claudius Huber

"If you can´t make your app run faster, make it at least look & feel extremly fast"

twitter: @thomasclaudiush
homepage: www.thomasclaudiushuber.com
author of: ultimate Windows Store Apps handbook | ultimate WPF handbook | ultimate Silverlight handbook

Answer 3

Hi Cheese,

my solution from above you can also put into an extension method:

 public static class ArrayExtensions
    {
        public static T?[] ToNullableArray<T>(this T[] array) where T : struct
        {
            return array.Select(i => (T?)i).ToArray();
        }
    }

And then use it on any value type array like this:

  int[] yourIntarry = new int[] { 1, 2, 3 };
  int?[] converted = yourIntarry.ToNullableArray();

:-)

---

Thomas Claudius Huber

"If you can´t make your app run faster, make it at least look & feel extremly fast"

twitter: @thomasclaudiush
homepage: www.thomasclaudiushuber.com
author of: ultimate Windows Store Apps handbook | ultimate WPF handbook | ultimate Silverlight handbook

Answer 4

Maybe one of the dbTypes may work like VarNumeric

namespace System.Data
{
    // Summary:
    //     Specifies the data type of a field, a property, or a Parameter object of
    //     a .NET Framework data provider.
    public enum DbType
    {
        // Summary:
        //     A variable-length stream of non-Unicode characters ranging between 1 and
        //     8,000 characters.
        AnsiString = 0,
        //
        // Summary:
        //     A variable-length stream of binary data ranging between 1 and 8,000 bytes.
        Binary = 1,
        //
        // Summary:
        //     An 8-bit unsigned integer ranging in value from 0 to 255.
        Byte = 2,
        //
        // Summary:
        //     A simple type representing Boolean values of true or false.
        Boolean = 3,
        //
        // Summary:
        //     A currency value ranging from -2 63 (or -922,337,203,685,477.5808) to 2 63
        //     -1 (or +922,337,203,685,477.5807) with an accuracy to a ten-thousandth of
        //     a currency unit.
        Currency = 4,
        //
        // Summary:
        //     A type representing a date value.
        Date = 5,
        //
        // Summary:
        //     A type representing a date and time value.
        DateTime = 6,
        //
        // Summary:
        //     A simple type representing values ranging from 1.0 x 10 -28 to approximately
        //     7.9 x 10 28 with 28-29 significant digits.
        Decimal = 7,
        //
        // Summary:
        //     A floating point type representing values ranging from approximately 5.0
        //     x 10 -324 to 1.7 x 10 308 with a precision of 15-16 digits.
        Double = 8,
        //
        // Summary:
        //     A globally unique identifier (or GUID).
        Guid = 9,
        //
        // Summary:
        //     An integral type representing signed 16-bit integers with values between
        //     -32768 and 32767.
        Int16 = 10,
        //
        // Summary:
        //     An integral type representing signed 32-bit integers with values between
        //     -2147483648 and 2147483647.
        Int32 = 11,
        //
        // Summary:
        //     An integral type representing signed 64-bit integers with values between
        //     -9223372036854775808 and 9223372036854775807.
        Int64 = 12,
        //
        // Summary:
        //     A general type representing any reference or value type not explicitly represented
        //     by another DbType value.
        Object = 13,
        //
        // Summary:
        //     An integral type representing signed 8-bit integers with values between -128
        //     and 127.
        SByte = 14,
        //
        // Summary:
        //     A floating point type representing values ranging from approximately 1.5
        //     x 10 -45 to 3.4 x 10 38 with a precision of 7 digits.
        Single = 15,
        //
        // Summary:
        //     A type representing Unicode character strings.
        String = 16,
        //
        // Summary:
        //     A type representing a time value.
        Time = 17,
        //
        // Summary:
        //     An integral type representing unsigned 16-bit integers with values between
        //     0 and 65535.
        UInt16 = 18,
        //
        // Summary:
        //     An integral type representing unsigned 32-bit integers with values between
        //     0 and 4294967295.
        UInt32 = 19,
        //
        // Summary:
        //     An integral type representing unsigned 64-bit integers with values between
        //     0 and 18446744073709551615.
        UInt64 = 20,
        //
        // Summary:
        //     A variable-length numeric value.
        VarNumeric = 21,
        //
        // Summary:
        //     A fixed-length stream of non-Unicode characters.
        AnsiStringFixedLength = 22,
        //
        // Summary:
        //     A fixed-length string of Unicode characters.
        StringFixedLength = 23,
        //
        // Summary:
        //     A parsed representation of an XML document or fragment.
        Xml = 25,
        //
        // Summary:
        //     Date and time data. Date value range is from January 1,1 AD through December
        //     31, 9999 AD. Time value range is 00:00:00 through 23:59:59.9999999 with an
        //     accuracy of 100 nanoseconds.
        DateTime2 = 26,
        //
        // Summary:
        //     Date and time data with time zone awareness. Date value range is from January
        //     1,1 AD through December 31, 9999 AD. Time value range is 00:00:00 through
        //     23:59:59.9999999 with an accuracy of 100 nanoseconds. Time zone value range
        //     is -14:00 through +14:00.
        DateTimeOffset = 27,
    }
}

---

jdweng

Answer 5

Here is another simple Linq solution.

int[] x = { 1, 2, 3 };
int?[] y = x.Cast<int?>().ToArray();

I hope this helps.

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