我vc里写了一个串口通讯的小程序，实现向串口写6个字符'h','e','l','l','o','!'

我把所有代码放在WinMain函数里可以成功写入串口，但我把初始化串口的一段程序封装到函数里实现时，却不成功，下面是两种方式的代码：

1，直接在WinMain函数中写，成功：
#include<windows.h>

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR pCmdLine,int iCmdShow)
{
HANDLE hComm;
DCB dcb;
COMMTIMEOUTS timeouts;

hComm=CreateFile("COM1",GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);
SetupComm(hComm,1024,1024);
timeouts.ReadIntervalTimeout=1000;
timeouts.ReadTotalTimeoutMultiplier=500;
timeouts.ReadTotalTimeoutConstant=5000;
timeouts.WriteTotalTimeoutMultiplier=500;
timeouts.WriteTotalTimeoutConstant=5000;
SetCommTimeouts(hComm,&timeouts);
GetCommState(hComm,&dcb);
dcb.BaudRate=CBR_9600;
dcb.ByteSize=8;
dcb.Parity=EVENPARITY;
dcb.StopBits=ONESTOPBIT;
SetCommState(hComm,&dcb);

char t_buffer[64]={'h','e','l','l','o','!'};
DWORD dwBytesWritten;
for(int i=0;i<64;i++)
{
WriteFile(hComm,t_buffer,1,&dwBytesWritten,NULL);
Sleep(10);
}
MessageBox(0,"File Write OK!","Comm",0);
}

2.我把初始化串口的过程放入函数,失败了：
#include <windows.h>

void OpenComm(HANDLE);

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR pCmdLine,int iCmdShow)
{
HANDLE hComm=NULL;

OpenComm(hComm);

char t_buffer[6]={'h','e','l','l','o','!'};
DWORD dwBytesWritten;
for(int i=0;i<6;i++)
{
WriteFile(hComm,t_buffer+i,1,&dwBytesWritten,NULL);
Sleep(10);
}
MessageBox(0,"File Write OK!","Comm",0);

return 0;
}

void OpenComm(HANDLE hComm)
{
DCB dcb;
COMMTIMEOUTS timeouts;

hComm=CreateFile("COM1",GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);
SetupComm(hComm,1024,1024);
timeouts.ReadIntervalTimeout=1000;
timeouts.ReadTotalTimeoutMultiplier=500;
timeouts.ReadTotalTimeoutConstant=5000;
timeouts.WriteTotalTimeoutMultiplier=500;
timeouts.WriteTotalTimeoutConstant=5000;
SetCommTimeouts(hComm,&timeouts);
GetCommState(hComm,&dcb);
dcb.BaudRate=CBR_9600;
dcb.ByteSize=8;
dcb.Parity=EVENPARITY;
dcb.StopBits=ONESTOPBIT;
SetCommState(hComm,&dcb);
}