请教串口问题

Question

if(!WriteFile(hCom,buffer,length,&leng,&Overlapped))
buff.Format( buff, "  %d\n", GetLastError());
MessageBox(buff);// 写串口
// WriteFile(hCom,buffer,length,&leng,&Overlapped);
CloseHandle(hCom);上面的代码很怪异，当用if(!WriteFile(hCom,buffer,length,&leng,&Overlapped))
buff.Format( buff, "  %d\n", GetLastError());
MessageBox(buff);// 写串口
时串口输出正常，
而把上面的注释掉，用WriteFile(hCom,buffer,length,&leng,&Overlapped);
就不会在串口输出东西,不知道为什么，请大家来说说

Answer 1

没区别啊，只是判断了一下写没写进去if(!WriteFile(hCom,buffer,length,&leng,&Overlapped)) //写串口
buff.Format( buff, "  %d\n", GetLastError()); //如果错误，得到错误信息
MessageBox(buff);                        //不管错不错，显示提示？？？
// WriteFile(hCom,buffer,length,&leng,&Overlapped); //正常应该是上面那样写，这样写错了也不知道
CloseHandle(hCom); 

Answer 2

我觉得你的代码写的很奇怪if(!WriteFile(hCom,buffer,length,&leng,&Overlapped)) 
buff.Format( buff, "  %d\n", GetLastError()); 
MessageBox(buff);// 写串口 
// WriteFile(hCom,buffer,length,&leng,&Overlapped); 
CloseHandle(hCom); 你这样，与
if(!WriteFile(hCom,buffer,length,&leng,&Overlapped)) 
{
   buff.Format( buff, "  %d\n", GetLastError()); 
}
MessageBox(buff);// 写串口 
// WriteFile(hCom,buffer,length,&leng,&Overlapped); 
CloseHandle(hCom);这样作用是一样的，请问你的本意是这样吗？还是你的本意是：
if(!WriteFile(hCom,buffer,length,&leng,&Overlapped)) 
{
   buff.Format( buff, "  %d\n", GetLastError());     MessageBox(buff);// 写串口 
    // WriteFile(hCom,buffer,length,&leng,&Overlapped); 
    CloseHandle(hCom);
}这样写，和
WriteFile(hCom,buffer,length,&leng,&Overlapped);   buff.Format( buff, "  %d\n", GetLastError());     MessageBox(buff);// 写串口 
    // WriteFile(hCom,buffer,length,&leng,&Overlapped); 
    CloseHandle(hCom);这样写结果是一样的

Answer 3

注意
true 和false判断0代表FALSE 
而不等于0都为TRUE 
明白了吧
小孩