I have code running that constantly throws an Access Violation on Windows XP. This exception only occurs however after around 10 to 20 thousand times running this function. I can catch the exception but want to get rid of it completely, however cannot figure out where it is coming from. Code is below (str is a simple string parser). Any help is greatly appreciated.

//--------------------------------------------------------

        unsigned char *inbuffer;
        AnsiString tmp;
        struct timeval current;
        inbuffer = new unsigned char[Count+2];
        myComPort->Read(inbuffer, Count);
        str.reset();
        try {
        if(Form2->mode == TForm2::HEX_MODE && !Form2->BufferDisabled->Checked){
                for(int i=0; i<Count; i++){
                        tmp.sprintf("%0x ", inbuffer[i]);
                        if(tmp.Length() < 3)
                                tmp = AnsiString("0") + tmp;
                        str << tmp.c_str() << " ";
                }
                if(Form2->ReceiveBuffer.Length() + str.length() < Form2->MaxBufLen){
                        Form2->ReceiveBuffer += AnsiString(str.c_str()).UpperCase();
                }
                else{
                        unsigned int n=0;
                        for(int count=0;n<=str.length();count++)
                                n += (*(Form2->Memo->Lines))[count].Length();
                        Form2->ReceiveBuffer.Delete(0, n);
                        Form2->ReceiveBuffer += AnsiString(str.c_str()).UpperCase();
                }
        }
        else if(Form2->mode == TForm2::ASCII_MODE && !Form2->BufferDisabled->Checked){
                inbuffer[Count] = '\0';
                if(Form2->ReceiveBuffer.Length() + strlen((char*)inbuffer) > Form2->MaxBufLen){
                        Form2->ReceiveBuffer.Delete(0, strlen((char*)inbuffer));
                }
                Form2->ReceiveBuffer += AnsiString((char*)inbuffer);
                if(Form2->logdata){
                        std::ofstream outfile;
                        outfile.open(Form2->LogFileName.c_str(), std::ofstream::out | std::ofstream::app);
                        outfile << (char*)inbuffer;
                        outfile.close();
                }
        }
        }
        catch (const EAccessViolation & vae)
        {
                ShowMessage("Misread message");
        } 

Is  Form2->ReceiveBuffer  AnsiString?  If this is AnsiString,  the first  argument  in Delete has to be  larger than 0 and less than Length of the AnsiString. See help
 

Thanks a lot, that solved the problem. I guess I'm so used to Java and string indexes starting at 0 that I didn't even consider the possibility that this could be the source of the problem.