How do I change an object to a double

Question

1.00/5 (1 vote)

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A DataTable has an output as an Object.
I want to convert it to a Double.

These gave a Cast error:

C#

Convert.ToDouble(dt.Rows[i][dc]);

C#

(double)dt.Rows[i][dc];

Is there any way of changing an Object to a Double?

C#

double[,] f = new double[10000,10000];
foreach (DataColumn dc in dt.Columns)
{
    h = h + 1;
        for (int i = 0; i<=1500; i++)
        {
            f[h, i] = Convert.ToDouble(dt.Rows[i][dc]);                    }
    }
}

What I have tried:

C#

Convert.ToDouble(dt.Rows[i][dc]);

C#

(double)dt.Rows[i][dc];

Posted 1-May-16 1:43am

teledexterus

Updated 1-May-16 19:12pm

v3

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Comments

Karthik_Mahalingam 2-May-16 0:57am

what is the exact error message?

3 solutions

Solution 1

dc is a DataColumn type, not a string or numeric value. So you can't do this:

C#

dt.Rows[i][dc]

because dc is not a valid index expression.
Probably you want this:

C#

(double) dt.Rows[i][dc.Ordinal]

Posted 1-May-16 2:28am

OriginalGriff

Comments

teledexterus 1-May-16 8:43am

Even with Ordinal you still get a Cast error. Is there any other way to covert a datatable object to an array double? Or something like decimal that will convert from object? I have numbers like 123.4567 in my datatable.

OriginalGriff 1-May-16 8:46am

Probably, you need to look at all your columns: does every cell in your datatable contain numeric values? Because you are running the same code - and so the same conversion - on every cell. If one column contains names, or dates, or ... it will fail.

Karthik_Mahalingam 2-May-16 0:56am

Hi OriginalGriff
DataRow class has 6 overloading to get the object of current row

public object this[DataColumn column] { get; set; }
public object this[int columnIndex] { get; set; }
public object this[string columnName] { get; set; }
public object this[DataColumn column, DataRowVersion version] { get; }
public object this[int columnIndex, DataRowVersion version] { get; }
public object this[string columnName, DataRowVersion version] { get; }

so dt.Rows[i][dc] should work and it works, i have tested it.

JFI :)

Thanks
karthik

Solution 3

Convert.ToDouble(dt.Rows[i][dc].Tostring());

this will solve your problem+

Posted 1-May-16 19:12pm

Member 12108660

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Karthik_Mahalingam · Accepted Answer · 2016-05-01T19:03:00

The below code will take care of casting exception, but you will have to make sure that the table has valid numbers

C#

double[,] f = new double[10000, 10000];
           foreach (DataColumn dc in dt.Columns)
           {
               h = h + 1;
               for (int i = 0; i <= 1500; i++)
               {
                   string value = dt.Rows[i][dc] + "";
                   double d = 0;
                   double.TryParse(value, out d);
                   f[h, i] = d;
               }
           }