#include "afx.h"
void main()
{
 OVERLAPPED gOverLapped;
 HANDLE hFile;
 DCB MonDCB;
 COMMTIMEOUTS MonCommTimeOuts;
 char inBuffer[20];
 unsigned long nBytesToRead=20;
 unsigned long nBytesRead=0;
 hFile=CreateFile("COM2",GENERIC_WRITE|GENERIC_READ,0,NULL,OPEN_EXISTING,0,NULL);
 if(hFile==INVALID_HANDLE_VALUE)
 {
  int ErreurCreateFile=GetLastError();
 }
 int Erreur1=GetCommState(hFile,&MonDCB);
 if(Erreur1==0)
 {
  int ErreurGetCommState=GetLastError();
 }
 MonDCB.BaudRate=CBR_9600;
 MonDCB.Parity=0;
 MonDCB.ByteSize=8;
 MonDCB.StopBits=0;
 int Erreur2=SetCommState(hFile,&MonDCB);
 if(Erreur2==0)
 {
  int ErreurSetCommState=GetLastError();
 }
 int Erreur3=GetCommTimeouts(hFile,&MonCommTimeOuts);
 if(Erreur3==0)
 {
  int ErreurGetCommState=GetLastError();
 }
 MonCommTimeOuts.ReadIntervalTimeout=500;
 MonCommTimeOuts.ReadTotalTimeoutMultiplier=1000;
 MonCommTimeOuts.ReadTotalTimeoutConstant=0;
 int Erreur4=SetCommTimeouts(hFile,&MonCommTimeOuts);
 if(Erreur4==0)
 {
  int ErreurSetCommTimeouts=GetLastError();
 }
// set up overlapped structure fields  
// to simplify this sample, we'll eschew an event handle  
gOverLapped.Offset     = 0;  
gOverLapped.OffsetHigh = 20;  
gOverLapped.hEvent     = NULL;  
int i;
for(i=0;i<=18;i++)
{
 inBuffer[i]=' ';
}
// attempt an asynchronous read operation  
DWORD bResult;
bResult=ReadFile(hFile, &inBuffer, nBytesToRead, &nBytesRead,  
    &gOverLapped) ;  
// if there was a problem, or the async. operation's still pending ...  
if (!bResult)  
{  
 DWORD dwError;
    // deal with the error code  
    switch (dwError = GetLastError())  
    {  
        case ERROR_HANDLE_EOF:  
        {  
            // we're reached the end of the file  
            // during the call to ReadFile  
 
            // code to handle that  
        }  
        case ERROR_IO_PENDING:  
        {  
            // asynchronous i/o is still in progress  
             // do something else for a while  
 //           GoDoSomethingElse() ;  
             // check on the results of the asynchronous read  
            bResult = GetOverlappedResult(hFile, &gOverLapped,  
                &nBytesRead, FALSE) ;  
             // if there was a problem ...  
            if (!bResult)  
            {  
                // deal with the error code  
                switch (dwError = GetLastError())  
                {  
                    case ERROR_HANDLE_EOF:  
                    {  
                        // we're reached the end of the file  
                        //during asynchronous operation  
                    }  
                     // deal with other error cases  
                }  
            }  
        } // end case  
 
        // deal with other error cases  
    } // end switch  
} // end if  
CloseHandle(hFile);
}