Sample Win32 project

main.c

#include <windows.h>

// Enable visual styles (XP and later)
#pragma comment(linker,"\"/manifestdependency:type='win32' \
name='Microsoft.Windows.Common-Controls' version='6.0.0.0' \
processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")

const int windowWidth = 500;
const int windowHeight = 90;

const int ID_BUTTON = 1;

HWND g_TextField;

LRESULT CALLBACK windowListener(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
  switch (msg)
	{
	case WM_CLOSE:
		DestroyWindow(hwnd);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	case WM_COMMAND:
		// When the button is pressed, retrieve the text from the text field and show it
		if (LOWORD(wParam) == ID_BUTTON) {
			LPCSTR buffer[100];
			SendMessage(g_TextField, WM_GETTEXT, sizeof(buffer), (LPARAM) buffer);
			MessageBox(0, (LPCSTR) buffer, "Your message", MB_ICONINFORMATION);
		}
		break;
	default:
		return DefWindowProc(hwnd, msg, wParam, lParam);
	}
}

int CALLBACK WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	// Create simple new class for the window
	WNDCLASS windowClass;
	memset(&windowClass, 0, sizeof(windowClass));
	windowClass.lpfnWndProc = windowListener;
	windowClass.hInstance = hInstance;
	windowClass.lpszClassName = "SimpleWindow";
	RegisterClass(&windowClass);

	// Calculate the position of the window to center it
	RECT screenRect;
	GetWindowRect(GetDesktopWindow(), &screenRect);
	int x = screenRect.right / 2 - windowWidth / 2;
	int y = screenRect.bottom / 2 - windowHeight / 2;
	
	// Create a visible non-resizable window
	DWORD style = WS_OVERLAPPEDWINDOW - (WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_THICKFRAME);
	HWND window = CreateWindow("SimpleWindow", "Simple Window", style | WS_VISIBLE, x, y, windowWidth, windowHeight, NULL, NULL, hInstance, NULL);

	// Create a text field
	g_TextField = CreateWindowEx(WS_EX_CLIENTEDGE, "EDIT", "", WS_CHILD | WS_VISIBLE, 10, 10, windowWidth - 194, windowHeight - 56, window, NULL, NULL, NULL);	
	SendMessage(g_TextField, WM_SETTEXT, NULL, (LPARAM) "Hello, world!");
	
	HFONT textFont = CreateFont(26, 0, 0, 0, 0, FALSE, FALSE, FALSE, 0, 0, 0, 0, 0, "Arial");
	SendMessage(g_TextField, WM_SETFONT, (WPARAM) textFont, TRUE);

	// Create a button
	HWND button = CreateWindow("BUTTON", "Show message", WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON, windowWidth - 174, 10, 150, windowHeight - 56, window, (HMENU) ID_BUTTON, NULL, NULL);
	
	HFONT buttonFont = CreateFont(16, 0, 0, 0, 700, FALSE, FALSE, FALSE, 0, 0, 0, 0, 0, "Arial");
	SendMessage(button, WM_SETFONT, (WPARAM) buttonFont, TRUE);

	// Handle events
	MSG msg;
	while (GetMessage(&msg, NULL, 0, 0)) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	// Clean up
	DeleteObject(buttonFont);
	DeleteObject(textFont);

	return EXIT_SUCCESS;
}