原帖地址：http://bbs.csdn.net/topics/391012458
代码改了一下，问题还没有解决。于是重开一个贴
-----------------------------------------------------C#代码
namespace WpfApplication2
{
class MyClass1 : INotifyPropertyChanged
{
public MyClass1()
{
result="null";
}
private string result;
public string Result
{
get { return result; }
set { result = value;
if (PropertyChanged != null)
{
this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs("Result"));
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public class mytransdll
{
[DllImport("mytransdll.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
public static extern int mytransfunc(StringBuilder exportpath, StringBuilder importpath);
}
public partial class Main : Window
{
MyClass1 myout=new MyClass1 ();
private StringBuilder exportpath;
private StringBuilder importpath;
public Main()
{
InitializeComponent();
myout.Result = "there will show ,if transform is ok ";// Result 赋值应该放到Main的构造函数或者窗口的Loaded事件中赋值的。
//把结果binding上去。。。请注意，XAML里的binding并不能访问C#里的变量，而C#里的变量却可以访问XAML
Binding bind1 = new Binding();
bind1.Source = myout;
bind1.Path = new PropertyPath("Result");
this.MyLabel.SetBinding(Label.ContentProperty, bind1);
}
private void Button_Click_2(object sender, RoutedEventArgs e)
{
//int isornotsuccess = 1;
int isornotsuccess = mytransdll.mytransfunc(exportpath, importpath);
myout.Result = " Transforming,please wait....";
Binding bind3 = new Binding();
bind3.Source = myout;
bind3.Path = new PropertyPath("Result");
this.MyLabel.SetBinding(Label.ContentProperty, bind3); //按下按钮之后马上显示正在传输
if (isornotsuccess == 1)
{
myout.Result = exportpath.ToString() ;
Binding bind2 = new Binding();
bind2.Source = myout;
bind2.Path = new PropertyPath("Result");
this.MyLabel.SetBinding(Label.ContentProperty, bind2); //这里写成功后的反应
}
}
private void textBox1_KeyDown_1(object sender, KeyEventArgs e)
{
if (e.Key == Key.Enter) //key是一个类，这是一个类的判断
{
StringBuilder exportpath=new StringBuilder(this.textBox1.Text,200);
}
}
---------------------------------------------------C++编写的DLL
//
#include "stdafx.h"
#include "stdio.h"
#include"pcap.h"
#include<WinSock.h>
#include"packet32.h"
#include<Win32-Extensions.h>
#include "stdlib.h"
extern "C" _declspec(dllimport) int mytransfunc(char* exportpath,char* importpath);
int mytransfunc(char* exportpath,char* importpath)
{
//和EXPORTPATH无关的代码
char A[]="regenerate_original_picture.txt";
char PA[1024];
char exportpathvalue=*exportpath;
//！！！！高能，就是这句出问题。不管是用这种方法中转还是直接调用*exportpath都出现报错
sprintf(PA,"%s\\%s",exportpathvalue,A);//连接字符串
FILE *fpopen = fopen(PA, "rb");
//和EXPORTPATH无关的代码
}
-----------------------------------------问题
C#编写了一个UI界面，调用DLL的时候传入文件所在地址，然后由DLL对其操作
测试过DLL程序的正确性。
之前大神们说的，如使用stringbuilder，DllImport函数的参数的设定都不管用。有网友说是关于托管代码和非托管代码内存管理的问题。。。楼主是新手，不太明白，还请指教。
------解决思路----------------------
还没搞定？
------解决思路----------------------
[DllImport("mytransdll.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
public static extern int mytransfunc([MarshalAs(UnmanagedType.LPStr)]string exportpath, [MarshalAs(UnmanagedType.LPStr)]string importpath);
------解决思路----------------------
因为你的exportpath没有初始化，传了null到C++，引发Access Violation异常。
解决方法：
1、去掉75行StringBuilder本地声明：
[删]StringBuilder[/删] exportpath=new StringBuilder(this.textBox1.Text,200);
2、或者，更好的是，exportpath即用即拿(不用声明为类成员，也不需要textBox1_KeyDown_1事件）：
private void Button_Click_2(object sender, RoutedEventArgs e)
{
StringBuilder exportpath=new StringBuilder(this.textBox1.Text,200);
int isornotsuccess = mytransdll.mytransfunc(exportpath, importpath);
------解决思路----------------------
char exportpathvalue=*exportpath;
sprintf(PA,"%s\\%s",exportpathvalue,A);//连接字符串
这是另外的一个错误。
%s将期待一个字符串指针，但你传入了一个char(char的取值范围是0~255），小数值指针将导致’违规访问‘。