Datagridview multiplication two column and checking value

Question

I want to check values in grid columns when performing multiplication between Quantity and Price values. I have done this and it works perfectly!

But I have a problem when I enter a string value in column Quantity or after I edit the column and leave it empty. I am getting an error:

So how can I check the values and when the user types string, char or blank input, show a MessageBox with feedback?

Here is my code:

private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
        {
            int price, quantity, total;         

             quantity= int.Parse(dataGridView1.Rows[e.RowIndex].Cells["Quantity"].Value.ToString());
             cena = int.Parse(dataGridView1.Rows[e.RowIndex].Cells["Price"].Value.ToString());
             total = quantity * price ;

            dataGridView1.Rows[e.RowIndex].Cells["Total"].Value = total;
        }

When I enter an integer everything works OK...

If your data was in a datatable you could use an expression column to automatically multiply the total. Otherwise this is a dupe — Ňɏssa Pøngjǣrdenlarp, Sep 02 '16 at 20:43
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Ňɏssa Pøngjǣrdenlarp, Sep 02 '16 at 20:43
I know what is that exception. I need like i say how to check what type of value is entered in cell — Ivan, Sep 02 '16 at 20:51
If you just added some columns and did not set the datatype, they will all be string. use `TryParse` for cases where they enter letters or spaces (or force the type to some numerics) — Ňɏssa Pøngjǣrdenlarp, Sep 02 '16 at 21:02
Forget about `CellEndEdit` or all other events. Just use computed column in your `DataTable`. [`DataColumn.Expression`](https://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression(v=vs.110).aspx) is what you are looking for. — Reza Aghaei, Sep 03 '16 at 11:38
my cumns is not in `DataTable` becouse i manually create grid `dataGridView1.Columns[3].Name = "quatity"`.. etc — Ivan, Sep 03 '16 at 13:14
So create a `DataTable` first! Don't use `DataGridView` without data source. — Reza Aghaei, Sep 03 '16 at 13:45
Take a look at this post [How can I merge 2 data properties and show them in a single Column of DataGridView?](http://stackoverflow.com/a/39140273/3110834) — Reza Aghaei, Sep 03 '16 at 13:57
@Ivan Let me know if you have any question about linked post. — Reza Aghaei, Sep 04 '16 at 21:04

Vijai · Answer 1 · 2016-09-02T21:33:31.570

0

Try this, and assign some value if the input is not able to convert to int.

    private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
            {
                int price, quantity, total;         

   if(dataGridView1.Rows[e.RowIndex].Cells["Quantity"].Value != null)
    {
        if(!int.TryParse(dataGridView1.Rows[e.RowIndex].Cells["Quantity"].Value.ToString(), out quantity))
            {
                 quantity= 0;
            }
    }else
    {
        quantity= 0;
    }    
                             price = int.Parse(dataGridView1.Rows[e.RowIndex].Cells["Price"].Value.ToString());

                     total = quantity * price ;

                    dataGridView1.Rows[e.RowIndex].Cells["Total"].Value = total;
                }

edited Sep 02 '16 at 21:33

answered Sep 02 '16 at 21:14

Vijai

2,369
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This return the some error in both cases woth string and blanko cell – Ivan Sep 02 '16 at 21:16
Error when you leave the value blank or when you enter some string value? – Vijai Sep 02 '16 at 21:19
Error when i enter string. Error when i enter in edit mode cell and leave it empty – Ivan Sep 02 '16 at 21:20
I have included sample code only for price. Have you included the code change for both quantity and price? – Vijai Sep 02 '16 at 21:24
Am only need to edit quantity! I dont touch price col and total col – Ivan Sep 02 '16 at 21:25
May be NULL issue, updated the code handle it. Pls check now. – Vijai Sep 02 '16 at 21:34

Jack1987 · Answer 2 · 2016-09-02T22:14:57.043

0

Use the try... catch block code

        void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e){ 

           int price, quantity, total;         
           try {
                 quantity= int.Parse(dataGridView1.Rows[e.RowIndex].Cells["Quantity"].Value.ToString());
                 cena = int.Parse(dataGridView1.Rows[e.RowIndex].Cells["Price"].Value.ToString());
                 total = quantity * price ;

                 dataGridView1.Rows[e.RowIndex].Cells["Total"].Value = total;
           } catch(NullReferenceException)  { ... }
       }

You can do nullable type

int? price, quantity, total;

And read here

https://msdn.microsoft.com/en-us/library/b3h1hf19(v=vs.110).aspx

edited Sep 02 '16 at 22:14

answered Sep 02 '16 at 21:38

Jack1987

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This slove problem when col is blank but not slove when i enter `char` or `string`. When i enter char or string i get `An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll` `Additional information: Input string was not in a correct format.` – Ivan Sep 02 '16 at 22:21
The System.FormatException is because your code is not converting the string to integer, Int32.Parse(...) – Jack1987 Sep 06 '16 at 13:57

Datagridview multiplication two column and checking value

2 Answers2