Clearing a field with sendmessage

[gerdescm]

I am working on automating a program whose source I don't have. I have everything working except I am struggling with sending a message to two fields. I am able to send the characters using a cmdlet created by Dr. McCaffrey, which uses sendmessage.
The problem is that this appends the characters to the end of the field. I want to make another cmdlet that clears the field first so that I may then append the characters to it but I canot figure out how to do that with sendmesage and I was unable to find anything about that in the user32 library.

Thanks for the help all.

[answers4forums]

Hi Gerdescm,

I dont know which platform ur using.

in linux and other RTOS :- we can use message-ques for sending and receiving the messages.

ur problem: see have a buffer( file for storing the messages), before writing into buffer make sure u ask the question whether :
1. to append to the existing file,
2. to clear the earlier contents.

!!Sorry!! if i have not given the solution.

Regards,
Answers.

[gerdescm]

Hey, thanks for the response. I am running on windows XP, so that does not supply the answer sadly. to give a bit more detail on how it is working, the cmdlet is using the user32.dll library which has a sendmessage function contained within. The sendmessage function can do many things when interfacing with a window control (it can click buttons append to fields etc) but I cannot find documentation on how to select what it is to do or what capabilities it has. I believe (judging by the code) that the WM_CHAR = 0x0102 is what specifies that it should be appending characters to the field. Unfortunately I have not been able to find information on what I would need to specify to have it either clear the field or simply replace the contents of the field with what I specify. I have included the code of the cmdlet that appends characters below. Thanks again for your help!

[Cmdlet(VerbsCommunications.Send, "Chars")]
    public class SendCharsCommand : Cmdlet
    {
        private IntPtr handleControl;
        private string s;
 
        [Parameter(Position = 0)]
        public IntPtr HandleControl {
            get { return handleControl; }
            set { handleControl = value; }
        }
 
        [Parameter(Position = 1)]
        public string S {
            get { return s; }
            set { s = value; }
        }
 
        [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
        private static extern void SendMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
 
        protected override void ProcessRecord() {
            uint WM_CHAR = 0x0102;
            foreach (char c in s) {
                SendMessage(handleControl, WM_CHAR, c, 0);
            }
        }
    } // class SendCharsCommand
 

Hi Gerdescm,

I dont know which platform ur using.

in linux and other RTOS :- we can use message-ques for sending and receiving the messages.

ur problem: see have a buffer( file for storing the messages), before writing into buffer make sure u ask the question whether :
1. to append to the existing file,
2. to clear the earlier contents.

!!Sorry!! if i have not given the solution.

Regards,
Answers.