Filling listboxes (.NET) from file data

[dimitrisagelis_gmail]

Hello to all!

I want to fill a listbox from a .dat file but I am stuck!!!

method-id ShowListBox public.
       local-storage section.
       01 listItem         string.
      
       procedure division.
       open input pinakes.
       read pinakes invalid key invoke type MessageBox::Show("ERROR!!!").
       invoke listBox1::BeginUpdate.
       set listItem to kwd2.
       invoke listBox1::Items::Add(listItem).
       invoke listBox1::EndUpdate.
       close pinakes.
       end method.

What Am I doing wrong...?

PS. I am totally noob in Cobol programming!!!!

[Chris Glazier]

Your example looks correct to me. Is this a Windows Forms application or something else? (WPF, ASP.NET?)

You can also just bind a list to the listbox control so you don't have to populate it directly but you can certainly do it the way that you show here.

The following simple demo works for me so when I click a button the listbox will be populated with the records in the text file. If you have non-text data like COMP, COMP-3 etc. then you will need to convert it first.

    class-id popListbox.Form1 is partial
                 inherits type System.Windows.Forms.Form.

            select myfile assign to "listdata.dat"
		                 organization is line sequential
						 file status is file-status.
       fd myfile.
       01 myrecord.
	  05 mynum   pic 9(3).
	  05 myname  pic x(10).
       working-storage section.
       01 file-status  pic x(2).
       method-id NEW.
       procedure division.
           invoke self::InitializeComponent
           goback.
       end method.

       method-id button1_Click final private.
       procedure division using by value sender as object e as type System.EventArgs.
	   open input myfile
	   invoke listBox1::BeginUpdate
           perform until exit
              read myfile
		 at end
		    exit perform
		 not at end
		    invoke listBox1::Items::Add(myrecord)
               end-read
           end-perform
           invoke listBox1::EndUpdate
           close myfile
		   
       end method.
      
       end class.

[dimitrisagelis_gmail]

Hello Chris!
Thank you for the response. I found a solution. Here is my code:
method-id ShowComboBox public.
local-storage section.
01 listItem string.
01 flag pic x value "n".
procedure division.
open input pinakes.
move spaces to pin0.
perform aaaa until flag = "y".
start pinakes key is greater than pin0 invalid key invoke type MessageBox::Show("ERROR Den arxise").
aaaa.
read pinakes next at end go to rrrr
move "y" to flag.
invoke comboBox1::BeginUpdate.
set listItem to perstix.
invoke comboBox1::Items::Add(listItem).
invoke comboBox1::EndUpdate.
rrrr.
close pinakes.
end method.

I'm totaly new to cobol programming so I will have plenty of questions...! haha

[Chris Glazier · Accepted solution]

I am glad that you found a solution. Since you are new to COBOL programming, I would like to make a suggestion and that is to never use a go to statement in your code. There are structured programming constructs that have been in place for a long time now that allow for alternatives to this potential spaghetti code creator. Periods at the end of statements are also a source of errors. Use the scope terminators like end-if and end-perform where possible. The only place you really need a period in the procedure division is after a section or paragraph name and after the last statement in a section or paragraph.

For instance you could rewrite your code as something like the following:

    method-id ShowComboBox public.
    local-storage section.
    01 listItem string.
    procedure division.

        open input pinakes
        move spaces to pin0
        start pinakes key is greater than pin0 
           invalid key 
              invoke type MessageBox::Show("ERROR Den arxise")
              exit method
        end-start
        perform until exit
           read pinakes next 
              at end
                 close pinakes
                 exit perform
              not at end
                 invoke comboBox1::BeginUpdate
                 set listItem to perstix
                 invoke comboBox1::Items::Add(listItem)
                 invoke comboBox1::EndUpdate
           end-read
        end-perform
      end method.