MSDN Intro: Undefined Reference to WinMain#16 - c++

Question

I am following the MSDN tutorial for setting up a basic Windows application with C++, and it is not compiling properly in Code::Blocks. Similar questions have been asked here before, but I was unable to find any with a solution and I am able to provide a detail that I did not see any others providing.
For now I was able to get it working by converting their wWinMain function to WinMain, but I would like to know what is going on since my understanding is that WinMain is intended for 16-bit operating systems.
Their Code:
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
Working Code:
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR pCmdLine, int nCmdShow)
And The Full Sample Code:
ifndef UNICODE
#define UNICODE
#endif
#include <windows.h>
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
// Register the window class.
const wchar_t CLASS_NAME[] = L"Sample Window Class";
WNDCLASS wc = { };
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.lpszClassName = CLASS_NAME;
RegisterClass(&wc);
// Create the window.
HWND hwnd = CreateWindowEx(
0, // Optional window styles.
CLASS_NAME, // Window class
L"Learn to Program Windows", // Window text
WS_OVERLAPPEDWINDOW, // Window style
// Size and position
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
NULL, // Parent window
NULL, // Menu
hInstance, // Instance handle
NULL // Additional application data
);
if (hwnd == NULL)
{
return 0;
}
ShowWindow(hwnd, nCmdShow);
// Run the message loop.
MSG msg = { };
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
}
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1));
EndPaint(hwnd, &ps);
}
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
Tutorial URL: http://msdn.microsoft.com/en-us/library/windows/desktop/ff381409(v=vs.85).aspx
Thanks in advance for any assistance you can offer!