Question

Background

I am working on an application which use listView, and I have write some functions for make actions with items in lisyView. I have actions as OnClickCopyAllDomains and OnClickMarkAllDomains. This functions works with domains (listView items) and when listView contain more then 100.000 item I feel how working speed goes down. So below I will show you functions, and I want you to give me advance how I can improve speed of functions?

OnClickMarkAllDomains

This function set listView items checked state to true.

System::Void MainForm::OnClickMarkAllDomains(System::Object^  sender, System::EventArgs^  e) {
        for( int i=0; i<listViewDomainsInfo->Items->Count; ++i )
            listViewDomainsInfo->Items[i]->Checked = true;
    }

OnClickCopyAllDomains

In this function I copy listView items (domains) to the clipboard, I if domains count is more then 100.000 I wait for 5 minutes till action ends.

System::Void MainForm::OnClickCopyAllDomains(System::Object^  sender, System::EventArgs^  e) {
        int itemsCount                  = listViewDomainsInfo->Items->Count;
        System::String^ outputClipboard = System::String::Empty;

        for( int i=0; i<itemsCount; ++i ) {
            outputClipboard += listViewDomainsInfo->Items[i]->Text + "\r\n";
        }

        if( !System::String::IsNullOrEmpty( outputClipboard ) ) {
            try {
                System::Windows::Forms::Clipboard::SetText( outputClipboard );
            }
            catch( ... ) { }
        }
    }

Question

How I can make my functions better, increase their speed ?

Answer 1

Call listViewDomainsInfo->BeginUpdate() before your loops and listViewDomainsInfo->EndUpdate() after.

Also, string concatenation as you’re using it is extremely inefficient. Make outputClipboard a System::Text::StringBuilder rather than a System::String.