使用WM_COPYDATA進行程序間通訊必須依賴Windows的訊息機制，不過此方法可以傳輸大量資料，而且實現簡單。

以下示例修改自Windows官方文件。

首先建立2個Windows桌面程式，為了示例的簡單，將字元型別修改為多位元組（預設為unicode）。

傳送端：

#define MYDISPLAY 1
typedef struct tagMyRec {
    char s1[64];
    char s2[64];
    DWORD n;
} MYREC;

VOID CopyData(HWND hWnd) {

    COPYDATASTRUCT myCDS = {0};
    MYREC myRec 
 
= {0};

    // Put data into data structure
    auto hResult = StringCbCopy(myRec.s1, sizeof(myRec.s1), "Claude");
    if (hResult != S_OK) {
        return ;
    }

    hResult = StringCbCopy(myRec.s2, sizeof(myRec.s2), "Bell");
    if (hResult != S_OK) {
        return ;
    }

    myRec.n = 99;

    
 
// Fill COPYDATA structure
    myCDS.dwData = MYDISPLAY;
    myCDS.cbData = sizeof(myRec);
    myCDS.lpData = &myRec;

    auto hwDispatch = FindWindow("RECEIVER", "r");
    if (hwDispatch != NULL) {
        SendMessage(hwDispatch, 
            WM_COPYDATA, 
            (WPARAM)hWnd, 
            (LPARAM)(LPVOID)
 
&myCDS);
    }
    else {
        MessageBox(hWnd, "Can't send WM_COPYDATA", "MyApp", MB_OK);
    }
}

////////////////////////

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // Parse the menu selections:
            switch (wmId)
            {
            case IDM_ABOUT:
                //DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                CopyData(hWnd);

出於示例的簡化目的，直接使用IDM_ABOUT觸發拷貝資料訊息.

接收端：

#define MYDISPLAY 1
typedef struct tagMyRec {
    char s1[64];
    char s2[64];
    DWORD n;
} MYREC;

VOID HandleCopyData(HWND hWnd, WPARAM wparam, LPARAM lparam) {
    auto pCDS = (PCOPYDATASTRUCT)lparam;
    switch (pCDS->dwData) {
    case MYDISPLAY: {
        auto myRec = (MYREC*)pCDS->lpData;
        MessageBox(hWnd, myRec->s1, myRec->s2, MB_OK);
        break;
    }
    }
}

///////////////////////////////

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COPYDATA:
        HandleCopyData(hWnd, wParam, lParam);
        break;

接收端只要在訊息處理函式中直接收一下資料就行了。