C / C++ / MFC

// DLL strlib.c

#include <windows.h>
#include <wchar.h>
#include "strlib.h"

// Shared memory section (requires /SECTION:shared, RWS in link options)
#pragma data_seg ("shared")
int iTotal = 0;
WCHAR szStrings[MAX_STRINGS][MAX_LENGTH + 1] = { '\0' };
#pragma data_seg ()

#pragma comment(linker, "/SECTION:shared, RWS")

int WINAPI DllMain(HINSTANCE hInstance, DWORD fdwReason, PVOID pvReserved)
{
	return TRUE;
}

EXPORT BOOL CALLBACK AddStringA(PCSTR pStringIn)
{
	BOOL bReturn;
	int iLength;
	PWSTR pWideStr;

	// Convert string to Unicode and call AddStringW
	iLength = MultiByteToWideChar(CP_ACP, 0, pStringIn, -1, NULL, 0);
	pWideStr = malloc(iLength);
	MultiByteToWideChar(CP_ACP, 0, pStringIn, -1, pWideStr, iLength);
	bReturn = AddStringW(pWideStr);
	free(pWideStr);

	return bReturn;
}

EXPORT BOOL CALLBACK AddStringW(PCWSTR pStringIn)
{
	PWSTR pString;
	int i, iLength;

	if (iTotal == MAX_STRINGS - 1)
		return FALSE;

	if ((iLength = wcslen(pStringIn)) == 0)
		return FALSE;

	// Allocate memory for storing string, copy it, convert to upper case
	pString = malloc(sizeof (WCHAR) * (1 + iLength));
	wcscpy(pString, pStringIn);
	_wcsupr(pString);

	// Alphabetize the strings
	for (i = iTotal; i > 0; i--)		// u knizi je i-
	{
		if (wcscmp(pString, szStrings[i - 1]) >= 0)
			break;

		wcscpy(szStrings[i], szStrings[i - 1]);
	}
	wcscpy(szStrings[i], pString);
	iTotal++;

	free(pString);
	return TRUE;
}

EXPORT BOOL CALLBACK DeleteStringA(PCSTR pStringIn)
{
	BOOL bReturn;
	int iLength;
	PWSTR pWideStr;

	// Convert string to Unicode and call DeleteStringW
	iLength = MultiByteToWideChar(CP_ACP, 0, pStringIn, -1, NULL, 0);
	pWideStr = malloc(iLength);
	MultiByteToWideChar(CP_ACP, 0, pStringIn, -1, pWideStr, iLength);
	bReturn = DeleteStringW(pWideStr);
	free(pWideStr);

	return bReturn;
}

EXPORT BOOL CALLBACK DeleteStringW(PCWSTR pStringIn)
{
	int i, j;

	if (0 == wcslen(pStringIn))
		return FALSE;

	for (i = 0; i < iTotal; i++)
		if (_wcsicmp(szStrings[i], pStringIn) == 0)
			break;

	// If given string is not in list, return without taking action
	if (i == iTotal)
		return FALSE;

	// Else adjust list downward
	for (j = i; j < iTotal; j++)
		wcscpy(szStrings[j], szStrings[j + 1]);

	szStrings[iTotal--][0] = '\0';
	return TRUE;
}

EXPORT int CALLBACK GetStringsA(GETSTRCB pfnGetStrCallBack, PVOID pParam)
{
	BOOL bReturn;
	int i, iLength;
	PSTR pAnsiStr;

	for (i = 0; i < iTotal; i++)
	{
		// Convert string from Unicode
		iLength = WideCharToMultiByte(CP_ACP, 0, szStrings[i], -1, NULL, 0, NULL, NULL);
		pAnsiStr = malloc(iLength);
		WideCharToMultiByte(CP_ACP, 0, szStrings[i], -1, pAnsiStr, iLength, NULL, NULL);

		// Call callback function
		bReturn = pfnGetStrCallBack(pAnsiStr, pParam);

		if (bReturn == FALSE)
			return i + 1;

		free(pAnsiStr);
	}
	return iTotal;
}

EXPORT int CALLBACK GetStringsW(GETSTRCB pfnGetStrCallBack, PVOID pParam)
{
	BOOL bReturn;
	int i;

	for (i = 0; i < iTotal; i++)
	{
		bReturn = pfnGetStrCallBack(szStrings[i], pParam);

		if (bReturn == FALSE)
			return i + 1;
	}
	return iTotal;
}


// strlib.h
#ifdef __cplusplus
	#define EXPORT extern "C" __declspec (dllexport)
#else
	#define EXPORT __declspec (dllexport)
#endif

#define MAX_STRINGS 256
#define MAX_LENGTH 63

// The callback function type definition uses generic strings
typedef BOOL (CALLBACK * GETSTRCB) (PCTSTR, PVOID);

// Each function has ANSI and UNICODE versions
EXPORT BOOL CALLBACK AddStringA(PCSTR);
EXPORT BOOL CALLBACK AddStringW(PCWSTR);

EXPORT BOOL CALLBACK DeleteStringA(PCSTR);
EXPORT BOOL CALLBACK DeleteStringW(PCWSTR);

EXPORT int CALLBACK GetStringsA(GETSTRCB, PVOID);
EXPORT int CALLBACK GetStringsW(GETSTRCB, PVOID);

#ifdef UNICODE
	#define AddString AddStringW
	#define DeleteString DeleteStringW
	#define GetStrings GetStringsW
#else
	#define AddString AddStringA
	#define DeleteString DeleteStringA
	#define GetStrings GetStringsA
#endif


// Main program: strprog.c
#include <windows.h>
#include "strlib.h"
#include "resource.h"

typedef struct
{
	HDC hdc;
	int xText;
	int yText;
	int xStart;
	int yStart;
	int xIncr;
	int yIncr;
	int xMax;
	int yMax;
}
CBPARAM;

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);

TCHAR szAppName[] = TEXT("StrProg");
TCHAR szString[MAX_LENGTH + 1];

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
						 PSTR szCmdLine, int iCmdShow)
{
	HWND hwnd;
	MSG msg;
	WNDCLASS wc;

	wc.style				= CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc		= WndProc;
	wc.cbClsExtra		= 0;
	wc.cbWndExtra		= 0;
	wc.hInstance		= hInstance;
	wc.hIcon				= LoadIcon(NULL, IDI_APPLICATION);
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground	= (HBRUSH) GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName	= szAppName;
	wc.lpszClassName	= szAppName;

	if (!RegisterClass(&wc))
	{
		MessageBox(NULL, TEXT("This program requires Windows NT!"),
					  szAppName, MB_ICONERROR);
		return 0;
	}

	hwnd = CreateWindow(szAppName, TEXT("DLL Demonstration Program"),
							  WS_OVERLAPPEDWINDOW,
							  CW_USEDEFAULT, CW_USEDEFAULT,
							  CW_USEDEFAULT, CW_USEDEFAULT,
							  NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, iCmdShow);
	UpdateWindow(hwnd);

	while (GetMessage(&msg, NULL, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}

LRESULT CALLBACK DlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
		case WM_INITDIALOG:
			SendDlgItemMessage(hDlg, IDC_STRING, EM_LIMITTEXT, MAX_LENGTH, 0);
			return TRUE;

		case WM_COMMAND:
			switch (wParam)
			{
				case IDOK:
					GetDlgItemText(hDlg, IDC_STRING, szString, MAX_LENGTH);
					EndDialog(hDlg, TRUE);
					return TRUE;

				case IDCANCEL:
					EndDialog(hDlg, FALSE);
					return TRUE;
			}
	}
	return FALSE;
}

BOOL CALLBACK GetStrCallBack(PTSTR pString, CBPARAM* pcbp)
{
	TextOut(pcbp->hdc, pcbp->xText, pcbp->yText,
			  pString, lstrlen(pString));

	if ((pcbp->yText += pcbp->yIncr) > pcbp->yMax)
	{
		pcbp->yText = pcbp->yStart;
		if ((pcbp->xText += pcbp->xIncr) > pcbp->xMax)
			return FALSE;
	}
	return TRUE;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	static HINSTANCE hInst;
	static int cxChar, cyChar, cxClient, cyClient;
	static UINT iDataChangeMsg;
	CBPARAM cbparam;
	HDC hdc;
	PAINTSTRUCT ps;
	TEXTMETRIC tm;

	switch (message)
	{
		case WM_CREATE:
			hInst = ((LPCREATESTRUCT)lParam)->hInstance;
			hdc = GetDC(hwnd);
			GetTextMetrics(hdc, &tm);
			cxChar = (int) tm.tmAveCharWidth;
			cyChar = (int) (tm.tmHeight + tm.tmExternalLeading);
			ReleaseDC(hwnd, hdc);

			iDataChangeMsg = RegisterWindowMessage(TEXT("StrProgDataChange"));
			return 0;

		case WM_COMMAND:
			switch (wParam)
			{
				case IDM_ENTER:
					if (DialogBox(hInst, TEXT("EnterDlg"), hwnd, &DlgProc))
					{
						if (AddString(szString))
							PostMessage(HWND_BROADCAST, iDataChangeMsg, 0, 0);
						else
							MessageBeep(0);
					}
					break;

				case IDM_DELETE:
					if (DialogBox(hInst, TEXT("DeleteDlg"), hwnd, &DlgProc))
					{
						if (DeleteString(szString))
							PostMessage(HWND_BROADCAST, iDataChangeMsg, 0, 0);
						else
							MessageBeep(0);
					}
					break;
			}
			return 0;

		case WM_SIZE:
			cxClient = (int) LOWORD(lParam);
			cyClient = (int) HIWORD(lParam);
			return 0;

		case WM_PAINT:
			hdc = BeginPaint(hwnd, &ps);

			cbparam.hdc		= hdc;
			cbparam.xText	= cbparam.xStart = cxChar;
			cbparam.yText	= cbparam.yStart = cyChar;
			cbparam.xIncr	= cxChar * MAX_LENGTH;
			cbparam.yIncr	= cyChar;
			cbparam.xMax	= cbparam.xIncr * (1 + cxClient / cbparam.xIncr);
			cbparam.yMax	= cyChar * (cyClient / cyChar - 1);

			GetStrings((GETSTRCB) GetStrCallBack, (PVOID) &cbparam);

			EndPaint(hwnd, &ps);
			return 0;

		case WM_DESTROY:
			PostQuitMessage(0);
			return 0;

		default:
			if (message == iDataChangeMsg)
				InvalidateRect(hwnd, NULL, TRUE);
			break;
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}