C# - Determine biggest and smallest number in a DataTables (handling decimal values)

Unfortunately that doesn't quite work, as it believes:

-100.15

is a lower number than

-171.37


Just to confirm, for that output I used:

MessageBox.Show(dtData.Compute("Min(ColumnName)", string.Empty).ToString());


Am I maybe using the incorrect math function?

It sounds more likely that the problem will be with the way you are storing your values. Are you by any chance storing your values as a text-based datatype rather than a numeric type ?

I am, I wasn't aware DataTables could handle multiple data types though, which type would you recommend I change it to? Double? Other?

double should work ok.

As you have just discovered, DataTables can handle multiple data types which will affect the sorting order (especially for numbers stored as string).

Is there an easy way to convert an entire column to a specified data type?

Eg;

dtData.Column[1].DataType = Double;

Are you populating your DataTable manually or from a database ?

A bit long winded, but here we go...

I have a function, which reads text file, and does some string manipulation, and then dumps row by row into a DataTable, and then returns the DataTable to whatever calls the DataTable.

I then do the following to fill the live DataTable:

DataTable dtTemp = SVReader();
foreach (DataRow dr in dtTemp.Rows)
{
    string[] row = new string[] { dr[0].ToString(), dr[1].ToString() };
    dtData.Rows.Add(row);
}



Is it possible to make the change in that last loop? I've tried:

string[] row = new string[] { dr[0].ToString(), Convert.ToDouble(dr[1].ToString()) };

But that just throws errors.

when you created your column into the datatable object, what datatype have you provided?

Unspecified, possible defaulting to string?

I used:

dtData.Columns.Add(new DataColumn("columnName"));

Ok, just tried this:


object[] row = new object[] { dr[0].ToString(), Convert.ToDouble(dr[1].ToString()) };

Compiles and runs, but the result is once again, the same as before. Have I missed something?

Now THAT works, brilliant, thanks guys!!