Validate Check box before printing

james james

I have 3 checkboxes that at least one needs to be checked before printing. I have the check boxes linked to the Print button. when i click print a message box states to check one box. when i check the box nothing happens.

private void btnPrint_Click(object sender, EventArgs e)

{

try

{

if (!checkBox1.Checked && !checkBox2.Checked && !checkBox3.Checked)

{

MessageBox.Show("Please select one !");

}

catch (Exception ex)

{

printDocument1.PrintPage += printDocument1_PrintPage;

printDocument1.Print();

}

private void printDocument1_PrintPage_1(object sender, PrintPageEventArgs e)

{

try

{

e.PageSettings.Landscape = true;

Bitmap bm = new Bitmap(this.panel.Width, this.panel.Height);

panel.DrawToBitmap(bm, new Rectangle(0, 0, this.panel.Width, this.panel.Height));

e.Graphics.DrawImage(bm, 0, 0, bm.Width, bm.Height);

}

catch (Exception ex)

{

string s1 = ex.Message;

}

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Tapan Patel9y ago
I think you need to go through basics of Try Catch block.

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/try-catch

so how it works:

Anything you think could throw an error ( or something could go wrong with this code), you need to put those code line in try block and if that code throws an error , we use catch block to recieve that error and then you can either log that error or take appropriate action.

As those two lines were in catch block, and your code didn't throw any error, it never executed lines in catch block.
+1
Amit Gupta9y ago
That was a part of your working module i.e it invoke your print event and modify your rendering printing page, that you had coded in your exception's body. The catch part will only being invoked when there is any exception.
+1
james james9y ago
I got no error from the original code, could you explain for me and other edicational.
why did it not compile with the code below added?
//printDocument1.PrintPage += printDocument1_PrintPage;
//printDocument1.Print();
great work guys
0
james james9y ago
Thanks for the help guys thats exactly what i was missing.
0
Tapan Patel9y ago
Ofcourse you need OR conditions and then you need to take out below code from Catch block and put it in try block

printDocument1.PrintPage += printDocument1_PrintPage;
printDocument1.Print();
try
{
if (!checkBox1.Checked && !checkBox2.Checked && !checkBox3.Checked)
{
MessageBox.Show("Please select one !");
return; // Need to select one checkbox
}
printDocument1.PrintPage += printDocument1_PrintPage;
printDocument1.Print();

}
catch (Exception ex)
{
// You don't need this here.
//printDocument1.PrintPage += printDocument1_PrintPage;
//printDocument1.Print();
}
+1
Amit Gupta9y ago
Apart from that, it was also noticed that print event and your print method name are not matched, I was surprised, how it complies, doesn't you got any compilation error?

private void printDocument1_PrintPage(object sender, PrintPageEventArgs e)
+1
james james9y ago
the OR makes me loop through each of the check boxes but still not printing.
0
Amit Gupta9y ago
If it need to check the one of three checkboxes then use OR operator instead of AND

Edited:
private void btnPrint_Click(object sender, EventArgs e)
{
try
{
if (checkBox1.Checked || checkBox2.Checked || checkBox3.Checked)
{
     printDocument1.PrintPage += printDocument1_PrintPage;
     printDocument1.Print();

}
else
   MessageBox.Show("Please select one !");
}
catch (Exception ex)
{

}
}
+1