C++ WinAPI. Wrong text display in the listbox - c++

Question

I have a task to create a program which displays a list of descriptors of all windows in the system. I am getting this output:
Maybe it's wrong encoding?
Here's my code:
#include <windows.h>
ATOM RegMyWindowClass(HINSTANCE, LPCTSTR);
HWND hListBox;
HINSTANCE hin;
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
WCHAR str[255];
if (GetWindowTextW(hwnd, str, 255)) {
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER)))
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
return 1;
}
LRESULT CALLBACK WndProc(
HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_LBUTTONUP:
MessageBox(hWnd, TEXT("Вы кликнули!"), TEXT("событие"), 0);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_CREATE:
hListBox = CreateWindow("LISTBOX", "", WS_CHILD | WS_VISIBLE | LBS_NOTIFY | WS_VSCROLL,
0, 0, 400, 400, hWnd, (HMENU)1111, hin, NULL);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
LPCTSTR lpzClass = TEXT("My Window Class!");
if (!RegMyWindowClass(hInstance, lpzClass))
return 1;
RECT screen_rect;
GetWindowRect(GetDesktopWindow(), &screen_rect);
int x = screen_rect.right / 2 - 200;
int y = screen_rect.bottom / 2 - 200;
HWND hWnd = CreateWindow(lpzClass, TEXT("Window"),
WS_OVERLAPPEDWINDOW | WS_VISIBLE, x, y, 400, 400, NULL, NULL,
hInstance, NULL);
ShowWindow(hWnd, SW_SHOW);
EnumWindows(&EnumWindowsProc, 0);
if (!hWnd) return 2;
MSG msg = { 0 };
int iGetOk = 0;
while ((iGetOk = GetMessage(&msg, NULL, 0, 0)) != 0)
{
if (iGetOk == -1) return 3;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
ATOM RegMyWindowClass(HINSTANCE hInst, LPCTSTR lpzClassName)
{
WNDCLASS wcWindowClass = { 0 };
wcWindowClass.lpfnWndProc = (WNDPROC)WndProc;
wcWindowClass.style = CS_HREDRAW | CS_VREDRAW;
wcWindowClass.hInstance = hInst;
wcWindowClass.lpszClassName = lpzClassName;
wcWindowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wcWindowClass.hbrBackground = (HBRUSH)COLOR_APPWORKSPACE;
return RegisterClass(&wcWindowClass);
}
Any ideas how to fix this?

Answer 1

The problem is that you are compiling your project for ANSI, where TCHAR is an alias for CHAR, and are thus creating an ANSI-based ListBox, but you are sending Unicode strings to it. That is why you are seeing garbage in the output. You need to send ANSI strings to the ListBox, eg:
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER)))
CHAR str[255] = {};
if (GetWindowTextA(hwnd, str, 255)) {
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
}
return TRUE;
}
Alternatively:
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER))) {
CHAR str[255] = {};
if (IsWindowUnicode(hwnd)) {
WCHAR wstr[255] = {};
int len = GetWindowTextW(hwnd, wstr, 255);
if (len) {
len = WideCharToMultiByte(CP_ACP, 0, wstr, len+1, str, 255, NULL, NULL);
}
if (!len) {
return TRUE;
}
}
else if (!GetWindowTextA(hwnd, str, 255)) {
return TRUE;
}
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
return TRUE;
}
That being said, you are mixing ANSI, Unicode, and TCHAR APIs. You need to pick 1 API style and stick with it for everything, don't mix them (unless you ABSOLUTELY have to).
Since the majority of the code you have shown is already using TCHAR, then you can use TCHAR for everything (though, you really shouldn't, since TCHAR is meant for backwards compatibility with Win9x/ME which nobody uses anymore, and was intended only to help people migrate their code to Unicode. Modern code should not be using TCHAR at all):
#include <windows.h>
ATOM RegMyWindowClass(HINSTANCE, LPCTSTR);
HWND hListBox;
HINSTANCE hin;
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER))) {
TCHAR str[255];
if (GetWindowText(hwnd, str, 255)) {
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
}
return TRUE;
}
LRESULT CALLBACK WndProc(
HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_LBUTTONUP:
// this is one case where it doesn't make sense to use TCHAR
MessageBoxW(hWnd, L"Вы кликнули!", L"событие", 0);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_CREATE:
hListBox = CreateWindow(TEXT("LISTBOX"), TEXT(""), WS_CHILD | WS_VISIBLE | LBS_NOTIFY | WS_VSCROLL,
0, 0, 400, 400, hWnd, (HMENU)1111, hin, NULL);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
LPCTSTR lpzClass = TEXT("My Window Class!");
if (!RegMyWindowClass(hInstance, lpzClass))
return 1;
RECT screen_rect;
GetWindowRect(GetDesktopWindow(), &screen_rect);
int x = screen_rect.right / 2 - 200;
int y = screen_rect.bottom / 2 - 200;
HWND hWnd = CreateWindow(lpzClass, TEXT("Window"),
WS_OVERLAPPEDWINDOW | WS_VISIBLE, x, y, 400, 400, NULL, NULL,
hInstance, NULL);
ShowWindow(hWnd, SW_SHOW);
EnumWindows(&EnumWindowsProc, 0);
if (!hWnd) return 2;
MSG msg = { 0 };
int iGetOk = 0;
while ((iGetOk = GetMessage(&msg, NULL, 0, 0)) != 0)
{
if (iGetOk == -1) return 3;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
ATOM RegMyWindowClass(HINSTANCE hInst, LPCTSTR lpzClassName)
{
WNDCLASS wcWindowClass = { 0 };
wcWindowClass.lpfnWndProc = &WndProc;
wcWindowClass.style = CS_HREDRAW | CS_VREDRAW;
wcWindowClass.hInstance = hInst;
wcWindowClass.lpszClassName = lpzClassName;
wcWindowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wcWindowClass.hbrBackground = (HBRUSH)COLOR_APPWORKSPACE;
return RegisterClass(&wcWindowClass);
}
Otherise, use Unicode for everything:
#include <windows.h>
ATOM RegMyWindowClass(HINSTANCE, LPCWSTR);
HWND hListBox;
HINSTANCE hin;
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER))) {
WCHAR str[255];
if (GetWindowTextW(hwnd, str, 255)) {
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
}
return TRUE;
}
LRESULT CALLBACK WndProc(
HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_LBUTTONUP:
MessageBoxW(hWnd, L"Вы кликнули!", L"событие", 0);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_CREATE:
hListBox = CreateWindowW(L"LISTBOX", L"", WS_CHILD | WS_VISIBLE | LBS_NOTIFY | WS_VSCROLL,
0, 0, 400, 400, hWnd, (HMENU)1111, hin, NULL);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
LPCWSTR lpzClass = L"My Window Class!";
if (!RegMyWindowClass(hInstance, lpzClass))
return 1;
RECT screen_rect;
GetWindowRect(GetDesktopWindow(), &screen_rect);
int x = screen_rect.right / 2 - 200;
int y = screen_rect.bottom / 2 - 200;
HWND hWnd = CreateWindowW(lpzClass, L"Window",
WS_OVERLAPPEDWINDOW | WS_VISIBLE, x, y, 400, 400, NULL, NULL,
hInstance, NULL);
ShowWindow(hWnd, SW_SHOW);
EnumWindows(&EnumWindowsProc, 0);
if (!hWnd) return 2;
MSG msg = { 0 };
int iGetOk = 0;
while ((iGetOk = GetMessage(&msg, NULL, 0, 0)) != 0)
{
if (iGetOk == -1) return 3;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
ATOM RegMyWindowClass(HINSTANCE hInst, LPCWSTR lpzClassName)
{
WNDCLASSW wcWindowClass = { 0 };
wcWindowClass.lpfnWndProc = &WndProc;
wcWindowClass.style = CS_HREDRAW | CS_VREDRAW;
wcWindowClass.hInstance = hInst;
wcWindowClass.lpszClassName = lpzClassName;
wcWindowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wcWindowClass.hbrBackground = (HBRUSH)COLOR_APPWORKSPACE;
return RegisterClassW(&wcWindowClass);
}
Or, stick with ANSI for everything, if you need to maintain compatibility with existing code logic elsewhere in your project:
#include <windows.h>
ATOM RegMyWindowClass(HINSTANCE, LPCSTR);
HWND hListBox;
HINSTANCE hin;
BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam)
{
if (IsWindowVisible(hwnd) && (!GetWindow(hwnd, GW_OWNER))) {
CHAR str[255];
if (GetWindowTextA(hwnd, str, 255)) {
SendMessage(hListBox, LB_ADDSTRING, 0, (LPARAM)str);
}
}
return TRUE;
}
LRESULT CALLBACK WndProc(
HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_LBUTTONUP:
// this is one case where it doesn't make sense to use ANSI
MessageBoxW(hWnd, L"Вы кликнули!", L"событие", 0);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_CREATE:
hListBox = CreateWindowA("LISTBOX", "", WS_CHILD | WS_VISIBLE | LBS_NOTIFY | WS_VSCROLL,
0, 0, 400, 400, hWnd, (HMENU)1111, hin, NULL);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
LPCSTR lpzClass = "My Window Class!";
if (!RegMyWindowClass(hInstance, lpzClass))
return 1;
RECT screen_rect;
GetWindowRect(GetDesktopWindow(), &screen_rect);
int x = screen_rect.right / 2 - 200;
int y = screen_rect.bottom / 2 - 200;
HWND hWnd = CreateWindowA(lpzClass, "Window",
WS_OVERLAPPEDWINDOW | WS_VISIBLE, x, y, 400, 400, NULL, NULL,
hInstance, NULL);
ShowWindow(hWnd, SW_SHOW);
EnumWindows(&EnumWindowsProc, 0);
if (!hWnd) return 2;
MSG msg = { 0 };
int iGetOk = 0;
while ((iGetOk = GetMessage(&msg, NULL, 0, 0)) != 0)
{
if (iGetOk == -1) return 3;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
ATOM RegMyWindowClass(HINSTANCE hInst, LPCSTR lpzClassName)
{
WNDCLASSA wcWindowClass = { 0 };
wcWindowClass.lpfnWndProc = &WndProc;
wcWindowClass.style = CS_HREDRAW | CS_VREDRAW;
wcWindowClass.hInstance = hInst;
wcWindowClass.lpszClassName = lpzClassName;
wcWindowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
wcWindowClass.hbrBackground = (HBRUSH)COLOR_APPWORKSPACE;
return RegisterClassA(&wcWindowClass);
}