C# error: Operator '==' cannot be applied

Question

On Visual Studio C# Express when I run the script below, I get the following error message on the line saying:

if (ofd.ShowDialog() == true): Error 1 Operator '==' cannot be applied to operands of type 'System.Windows.Forms.DialogResult' and 'bool'

How could I solve this? Code below:

public override GH_ObjectResponse RespondToMouseDoubleClick(GH_Canvas sender, GH_CanvasMouseEvent e)
{
    System.Windows.Forms.OpenFileDialog ofd = new  System.Windows.Forms.OpenFileDialog();
    ofd.Multiselect = true;

    ofd.Filter = "Data Sources (*.ini)|*.ini*|All Files|*.*";
    if (ofd.ShowDialog() == true)
    {
        string[] filePath = ofd.FileNames;
        string[] safeFilePath = ofd.SafeFileNames;
    }
    return base.RespondToMouseDoubleClick(sender, e);
}

Answer 1

Replace it with:

if (ofd.ShowDialog() == DialogResult.OK)

ShowDialog method returns DialogResult enumeration, which has following members:

• None
• OK
• Cancel
• Abort
• Retry
• Ignore
• Yes
• No

Answer 2

Compare with on of the values defined for DialogResult like DialogResult.OK not boolean.

if (ofd.ShowDialog() == DialogResult.OK)
{

}

Possible values of DialogResults are given below. compare with the one you require.

DialogResult.None
DialogResult.OK
DialogResult.Cancel
DialogResult.Abort
DialogResult.Retry
DialogResult.Ignore
DialogResult.Yes
DialogResult.No

Answer 3

I suspect you've been reading the WPF OpenFileDialog.ShowDialog documentation where the method result is Nullable<bool>. If, however, you're using Windows Forms OpenFileDialog.ShowDialog, that returns DialogResult - which you clearly can't compare with bool.

Have a look at DialogResult and see what you actually want to do. Note that the documentation claims:

Return: DialogResult.OK if the user clicks OK in the dialog box; otherwise, DialogResult.Cancel.

... so those should be the only cases you need to consider.