并口控制

[tommy851213]

一下程序是控制并口 数据存储器的
我打开并口成功了
但是写入失败
请问问题出在哪儿？




// 44.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<windows.h>
#include<iostream.h>

void main()
{
unsigned long Num_Transfered;
OVERLAPPED overlapped;
unsigned char abc='0';
unsigned char *Signal = &abc;
unsigned char Read = 0;
HANDLE hPort;

overlapped.Internal = 0;
overlapped.InternalHigh = 0;
overlapped.Offset = 0;
overlapped.OffsetHigh = 0;
overlapped.hEvent = NULL;

hPort = CreateFile( "LPT1", GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED, NULL );
Sleep( 10 );
if( hPort==INVALID_HANDLE_VALUE )
{
cout<<"Port Open Failed!"<<endl;
//exit(0);
}
else
{

//Signal = 0;
BOOL b=false;
Num_Transfered = sizeof( Signal );
b=WriteFile( hPort,Signal, Num_Transfered, &Num_Transfered, &overlapped );
Sleep( 250 );
cout<<b<<endl;
b=ReadFile( hPort, &Read, Num_Transfered, &Num_Transfered, &overlapped );
cout<<b<<endl;
Sleep( 250 );
int a;
scanf("%d",&a);
/*Signal = 1;
WriteFile( hPort, &Signal, Num_Transfered, &Num_Transfered, &overlapped );
Sleep( 250 );
ReadFile( hPort, &Read, Num_Transfered, &Num_Transfered, &overlapped );
cout<<int(Read)<<endl;
Sleep( 250 ); */
}

CloseHandle( hPort );
}

[可口可乐]

unsigned char abc='0';
unsigned char *Signal = &abc;
这一句可能有问题。
abc是个char，
Signal本意是个字符串，指向abc，但abc并不是以'\0'结尾的字符串

同时Num_Transfered = sizeof( Signal );
得到的是Signal作为指针的长度，始终为4，
本意应该是Signal中字符的个数。

改成
unsigned char *Signal = "0";
Num_Transfered = strlen(Signal);
试试看

[knowledge_Is_Life]

不明LZ在说什么

[UltraBejing]

有点难度哦