进程间通信的方法有多种，其中，对于少量数据可以用WM_COPYDATA方便的实现通信(如果对于大量数据的话，由于SendMessage是阻塞的，只有接收方响应了消息，SendMessage才能返回，否则则一直阻塞，所以，对于大量数据来说，用SendMessage就容易造成窗口假死) 。

本例子分别用WM_COPYDATA 实现了两种数据类型的发送，一种为Cstring，另外一种为自定义的结构体Student：

//**********************************************************

#pragma pack(1)

struct Student {

char ID[10];

TCHAR   Name[20];

UINT      Age;

UINT      Grade;

char Room[5];

char Tel[12];

};

#pragma pack()

//**********************************************************

因为需要在接收方的OnCopyData()函数中区分发送的两种不同类型数据。所以就定义了以下两个常量：

#define STRING 1

发送方：

void CSendDataDlg::OnBtSend() //实现CString类型数据的发送

{

UpdateData(TRUE);

if (m_szData.IsEmpty()) {

m_szData = _T("Hello");

UpdateData(FALSE);

}

//     m_szData += '\0';

HWND hWndRcv = ::FindWindow(NULL,"Receiver");

if (hWndRcv == NULL) {

AfxMessageBox(_T("找不到接收窗口，发送不成功"));

return ;

}

COPYDATASTRUCT cpd;

cpd.dwData = STRING; //标志为CString类型

cpd.cbData = m_szData.GetLength() + 1;

//GetLength()只是取得实际字符的长度，没有包括'\0'.

cpd.lpData = (void*)m_szData.GetBuffer(cpd.cbData);

::SendMessage(hWndRcv,WM_COPYDATA,(WPARAM)this->m_hWnd,(LPARAM)&cpd);

m_szData.ReleaseBuffer();

AfxMessageBox(_T("发送成功"));

}

void CSendDataDlg::OnBtStu() //实现Student类型数据的发送

{

UpdateData();

m_szID += '\0';

m_szName += '\0';

m_szRoom += '\0';

m_szTel += '\0';

m_pStu = new Student();

strcpy(m_pStu->ID,m_szID.GetBuffer(m_szID.GetLength()));

_tcscpy(m_pStu->Name,m_szName.GetBuffer(m_szName.GetLength()));

strcpy(m_pStu->Room,m_szRoom.GetBuffer(m_szRoom.GetLength()));

strcpy(m_pStu->Tel,m_szTel.GetBuffer(m_szTel.GetLength()));

m_szID.ReleaseBuffer();m_szName.ReleaseBuffer();

m_szRoom.ReleaseBuffer();m_szTel.ReleaseBuffer();

m_pStu->Age = m_nAge;

m_pStu->Grade = m_nGrade;

HWND hWndRcv = ::FindWindow(NULL,"Receiver");

if (hWndRcv == NULL) {

AfxMessageBox(_T("找不到接收窗口，发送不成功"));

return ;

}

COPYDATASTRUCT cpd;

cpd.dwData = STUDENT;     // 标志为Student类型

cpd.cbData = sizeof(Student);

cpd.lpData = (PVOID)m_pStu;

::SendMessage(hWndRcv,WM_COPYDATA,(WPARAM)this->m_hWnd,(LPARAM)&cpd);

delete m_pStu;

AfxMessageBox(_T("发送成功"));

接收方：

在OnInitDialog方法中：

//***************************************************************

//初始化ListCtrl控件

LVCOLUMN column;

column.mask = LVCF_TEXT | LVCF_SUBITEM | LVCF_WIDTH;

column.cx = 80;

column.iSubItem = 0;

column.pszText = _T("ID");

m_ListCtl.InsertColumn(0,&column);

column.cx = 80;

column.pszText = _T("Name");

column.iSubItem = 1;

m_ListCtl.InsertColumn(1,&column);

column.cx = 55;

column.pszText = _T("Age");

column.iSubItem = 2;

m_ListCtl.InsertColumn(2,&column);

column.cx = 55;

column.pszText = _T("Grade");

column.iSubItem = 3;

m_ListCtl.InsertColumn(3,&column);

column.cx = 55;

column.pszText = _T("Room");

column.iSubItem = 4;

m_ListCtl.InsertColumn(4,&column);

column.cx = 80;

column.pszText = _T("Tel");

column.iSubItem = 5;

m_ListCtl.InsertColumn(5,&column);

BOOL CReceiverDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct)

{

switch (pCopyDataStruct->dwData) { // 接收到的是CString类型

case STRING:

m_szData += (LPCSTR)(pCopyDataStruct->lpData);

UpdateData(FALSE);

break;

case STUDENT:  // 接收到的是Student类型

CString id,name,room,tel;

UINT age,grade;

CString str;

Student* pStu = (Student*)(pCopyDataStruct->lpData);

id = pStu->ID;

name = pStu->Name;

room = pStu->Room;

tel = pStu->Tel;

age = pStu->Age;

grade = pStu->Grade;

LVITEM item;

// 把接收到的数据显示到ListCtrl控件上

item.mask = LVIF_TEXT;

int n = m_ListCtl.GetItemCount();

item.iItem = n;

item.iSubItem = 0;

item.pszText = id.GetBuffer(id.GetLength());

id.ReleaseBuffer();

m_ListCtl.InsertItem(&item);

m_ListCtl.SetItemText(n,1,name);

str.Format("%d",age);

m_ListCtl.SetItemText(n,2,str);

str.Format("%d",grade);

m_ListCtl.SetItemText(n,3,str);

m_ListCtl.SetItemText(n,4,room);

m_ListCtl.SetItemText(n,5,tel);

UpdateData(FALSE);

//delete pStu;

break;

}

//     return CDialog::OnCopyData(pWnd, pCopyDataStruct);

return TRUE;

}