how to minus two columns value in GridView

Question

1.00/5 (1 vote)

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how to minus column Cost,insuranceCost and store the result in a column Total for each row?!

myCode:

ServiceInsuranceList = new System.Data.DataTable();

C#

private void BtnAdd_Click(object sender, EventArgs e)
       {

             GrdServiceInsurance.DataSource = ServiceInsuranceList;
                for (int i = 0; i < GrdServiceInsurance.Rows.Count; ++i)
                {
 GrdServiceInsurance.Rows[i].Cells["Total"].Value =(Convert.ToInt32( GrdServiceInsurance.Rows[i].Cells["Cost"].Value.ToString())) -(Convert.ToInt32( GrdServiceInsurance.Rows[i].Cells["InsuranceCost"].Value.ToString())) 
                }

       }

But it does not work...
error "Object reference not set to an instance of an object."

Posted 5-May-14 22:01pm

je30ca

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Comments

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 6-May-14 4:09am

On which line?

je30ca 6-May-14 4:14am

GrdServiceInsurance.Rows[i].Cells["Total"].Value =(Convert.ToInt32( GrdServiceInsurance.Rows[i].Cells["Cost"].Value.ToString())) -(Convert.ToInt32( GrdServiceInsurance.Rows[i].Cells["InsuranceCost"].Value.ToString()))

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 6-May-14 5:57am

Okay do one thing now. While debugging in the immediate window, check the values for...

GrdServiceInsurance.Rows[i].Cells["Cost"].Value.ToString()

and

GrdServiceInsurance.Rows[i].Cells["InsuranceCost"].Value.ToString()

Do you see the correct values?

4 solutions

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kunal r somani · Answer 1 · 2014-05-06T01:05:00

Solution 3

first you have to check whether cost and insurance cost is not null or blank. if one of the null or blank then error come. so null or blank convert into 0 from DB side.

Posted 6-May-14 1:05am

kunal r somani

Peter Leow · Answer 2 · 2014-05-06T01:34:00

Solution 4

Check this out, half of it is similar to yours: Displaying Total in Footer of GridView and also Add Sum of columns(row vise) in last Column [^]

Posted 6-May-14 1:34am

Peter Leow

Manu Smriti · Answer 3 · 2014-05-05T22:08:00

Solution 1

i will suggest you to add one more column Total in your datatable itself and assign value using datatable iteration instead of gridview that will be fast & solve your problem.

In the above code GrdServiceInsurance.databind() is missing.

Posted 5-May-14 22:08pm

Manu Smriti

Comments

je30ca 6-May-14 5:38am

how to sum two columns value in datatable?!

Manu Smriti 6-May-14 6:04am

look at this you will get an idea, here in datatable we have column 'Total'.
I'm iterating thru' datatable , adding 2 in first column of datatable & storing it into Total Column
int sum;
int count=0;
foreach (var item in dtCombo.AsEnumerable())
{
sum = Convert.ToInt32(item[0]) + 2;
dtCombo.Rows[count++]["Total"] = sum;
}

lukeer · Answer 4 · 2014-05-05T22:13:00

Solution 2

Wrong place in your application to do the calculation. The code you show is part of the User Interface. Its purpose is displaying data and accepting user input. Don't do calculations here.

ServiceInsuranceList, if not totally ill-named, contains a list of objects. I don't know what objects, but they should be instances of a class that has properties for Cost and InsuranceCost.
Make this class have a property Total as well. Let it be read-only and let the class itself update Total whenever one of its dependencies (Cost and InsuranceCost) changes. Then let data binding do its magic.

Posted 5-May-14 22:13pm

lukeer

Comments

je30ca 6-May-14 4:50am

must be "total" a column of the table?!
now "Total" is just a column of DatagridView

lukeer 6-May-14 7:32am

But the DataGridView is data-bound. IIRC, you can't fill individual cells in that case. Instead you have to provide all data via the given data source.

However, before we get to that point, sort out the problem at hand:
break up the calculation so you get integer values for Cost, InsuranceCost and Total, calculate, assign to the correct cell. Then you should see what step throws the exception (that's just another way to do what Tadit Dash suggested).