/**********windows核心编程实例17-AppInst**********/
/***展示:应用程序如何知道在任一时刻有多少个自己的实例正在运行***/

#include <windows.h>
#include "resource.h"

int g_uMsgAppInstCountUpdate = WM_APP + 123;

#pragma data_seg("Shared")
volatile LONG g_lApplicationInstances = 0;
#pragma data_seg()

#pragma comment(linker, "/Section:Shared,RWS") // 引号内不能加空格

void DlgCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
    switch (id)
    {
    case IDCANCEL:
        EndDialog(hwnd, id);
        break;

    default:
        break;
    }
}

INT_PTR WINAPI DlgProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    if (uMsg == g_uMsgAppInstCountUpdate)
    {
        SetDlgItemInt(hwnd, IDC_COUNT, g_lApplicationInstances, FALSE);
    }

    switch (uMsg)
    {
    case WM_INITDIALOG:
        PostMessage(HWND_BROADCAST, g_uMsgAppInstCountUpdate, 0, 0);
        break;

    case WM_COMMAND:
        DlgCommand(hwnd, LOWORD(wParam), (HWND)lParam, uMsg);
        break;

    default:
        break;
    }

    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, PTSTR, int)
{
    g_uMsgAppInstCountUpdate = RegisterWindowMessage(TEXT("MsgAppInstCountUpdate"));

    InterlockedExchangeAdd(&g_lApplicationInstances , 1);

    DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1), NULL, DlgProc);

    InterlockedExchangeAdd(&g_lApplicationInstances, -1);

    PostMessage(HWND_BROADCAST, g_uMsgAppInstCountUpdate, 0, 0);

    return 0;
}

2011-08-10

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