#include <iostream>
#include <Windows.h>

using namespace std;

BOOL CALLBACK EnumChildProc(_In_ HWND hwnd, _In_ LPARAM lParam)
{
    char szTitle[MAX_PATH] = { 0 };
    char szClass[MAX_PATH] = { 0 };
    int nMaxCount = MAX_PATH;

    LPSTR lpClassName = szClass;
    LPSTR lpWindowName = szTitle;

    GetWindowTextA(hwnd, lpWindowName, nMaxCount);
    GetClassNameA(hwnd, lpClassName, nMaxCount);
    cout << "[Child window] window handle: " << hwnd << " window name: "
        << lpWindowName << " class name " << lpClassName << endl;

    return TRUE;
}


BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
     /* 
     Remarks
     The EnumWindows function does not enumerate child windows,
     with the exception of a few top-level windows owned by the
     system that have the WS_CHILD style.
     */
    char szTitle[MAX_PATH] = { 0 };
    char szClass[MAX_PATH] = { 0 };
    int nMaxCount = MAX_PATH;

    LPSTR lpClassName = szClass;
    LPSTR lpWindowName = szTitle;

    GetWindowTextA(hwnd, lpWindowName, nMaxCount);
    GetClassNameA(hwnd, lpClassName, nMaxCount);
    cout << "[Parent window] window handle: " << hwnd << " window name: "
        << lpWindowName << " class name " << lpClassName << endl;

    EnumChildWindows(hwnd, EnumChildProc, lParam);

    return TRUE;
}


int main(int argc, char *argv[])
{
    EnumWindows(EnumWindowsProc, 0);
    return 0;
}

Reference:
遍历Windows桌面上所有窗口