this code getting executed but not doing the action?

Question

1.00/5 (1 vote)

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this is to delete the data row with checkbox in datagridview

private void btndelete_Click(object sender, EventArgs e)
{

try
{
foreach (DataGridViewRow row in dataGridView1.Rows)
{
object cell = row.Cells["dgvdel"].Value;
if (cell =="yes")
{

if (MessageBox.Show("Want to delete","Don't", MessageBoxButtons.YesNo) == DialogResult.OK) ;
{
javidDataSet.sample_data.Rows[row.Index].Delete();
sample_dataTableAdapter.Update(javidDataSet);
}

}
}
}

catch (Exception ex)
{
}

}

its not entering into the messagebox loop...

Posted 10-Sep-15 21:02pm

Xaavier

Updated 10-Sep-15 21:06pm

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F-ES Sitecore 11-Sep-15 3:14am

Is this a website?

Xaavier 11-Sep-15 3:18am

no this is for winform.. after the comparison of cell values "yes".its not entering into messagebox...

Sergey Alexandrovich Kryukov 11-Sep-15 3:23am

catch (Exception e) {}
is a big abuse.
Hard-coded "dgvdel" and especially "yes" is also a big abuse. Apparently, you have some other "yes" in code. Do you understand that this is not maintainable?

General recipe is: use the debugger.

—SA

Xaavier 11-Sep-15 3:29am

actually i set true value of the column of the delete(column) as "yes"
without implementing try block and exception its not deleting.

1 solution

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OriginalGriff · Answer 1 · 2015-09-10T21:34:00

Solution 2

We can't solve this for you - we can't run that code in isolation and get teh same results you do with your data.

So start with the debugger.
Put a breakpoint on this line:

C#

if (cell =="yes")

And run your app. when it hits the breakpoint, it will stop, and let you look at exactly what is going on.
Look at the content of "cell" - is it a string? Does it contain "yes" in that exact text, or is the string "Yes", or "YES"?

I suspect that because cell is an object, it's doing a reference comparison between the value returned from your cell and the string "yes" - in which case try this instead:

C#

foreach (DataGridViewRow row in dataGridView1.Rows)
    {
    string cell = (string) row.Cells["dgvdel"].Value;
    if (cell.ToLower() == "yes")
        {

You are almost certainly getting a warning for this when you compile:

Possible unintended reference comparison

If so, then you should always treat warnings as errors to avoid this kind of problem.

Posted 10-Sep-15 21:34pm

OriginalGriff

Comments

Xaavier 11-Sep-15 3:43am

now i am getting executed but it shows Warning Possible unintended reference comparison; to get a value comparison, cast the left hand side to type 'string'

F-ES Sitecore 11-Sep-15 3:52am

If your cell is a string then you're better not using object at all

string cell = row.Cells["dgvdel"].Value.ToString();

OriginalGriff 11-Sep-15 4:01am

As I said you should!
The difference is like comparing two people: the simplest way is to do a Value Comparison - "are the names the same?"
So if look at the names of each, and they are both "John Smith" then the value comparison says "true". But does that mean they are the same person? No - if you do a Reference Comparison "Are these the same person?" then you will get "false".
Strings are normally compared using a Value comparison: each character in each string is compared, and they are the same if and only if every character pair matches identically.
But when one side is an object, you get a Reference comparison instead: the "pointer to the memory" for each is compared instead of the actual characters in the strings.

As I said: treat warnings as errors - the compiler does know better than you (and me!)
I have all my projects set to do this automatically - my projects will not compile with any warnings.
Open your project in the Solution Explorer pane, and double click the "Properties" branch.
In the resulting page, select the "Build" tab on the left.
Make sure that "Warning level" is set to "4" (the highest) and that "Treat warnings as errors" is set to "All".
Save and close the page.

Now when you compile, it won't let you do things like that which may have unintended side effects.