How can I do GUI programming in C? [closed]

This is guaranteed to have nothing to do with the compiler. All compilers do is compile the code that they are given. What you're looking for is a GUI library, which you can write code against using any compiler that you want.

Of course, that being said, your first order of business should be to ditch Turbo C. That compiler is about 20 years old and continuing to use it isn't doing you any favors. You can't write modern GUI applications, as it will only produce 16-bit code. All modern operating systems are 32-bit, and many are now 64-bit. It's also worth noting that 64-bit editions of Windows will not run 16-bit applications natively. You'll need an emulator for that; it's not really going to engender much feeling of accomplishment if you can only write apps that work in a DOS emulator. :-)

Microsoft's Visual Studio Express C++ is available as a free download. It includes the same compiler available in the full version of the suite. The C++ package also compiles pure C code.

And since you're working in Windows, the Windows API is a natural choice. It allows you to write native Windows applications that have access to the full set of GUI controls. You'll find a nice tutorial here on writing WinAPI applications in C. If you choose to go with Visual Studio, it also includes boilerplate code for a blank WinAPI application that will get you up and running quickly.

If you really care about learning to do this, Charles Petzold's Programming Windows is the canonical resource of the subject, and definitely worth a read. The entire Windows API was written in C, and it's entirely possible to write full-featured Windows applications in C. You don't need no stinkin' C++.

That's the way I'd do it, at least. As the other answers suggest, GTK is also an option. But the applications it generates are just downright horrible-looking on Windows.

EDIT: It looks like you're not alone in wanting to write "GUI" applications using an antiquated compiler. A Google search turns up the following library: TurboGUI: A GUI Framework for Turbo C/C++:

If you're required use Turbo C, this might be an option.

The most famous library to create some GUI in C language is certainly GTK.

With this library you can easily create some buttons (for your example). When a user clicks on the button, a signal is emitted and you can write a handler to do some actions.

Use win APIs in your main function:

1. RegisterClassEx() note: you have to provide a pointer to a function (usually called WndProc) which handles windows messages such as WM_CREATE, WM_COMMAND etc
2. CreateWindowEx()
3. ShowWindow()
4. UpdateWindow()

Then write another function which handles win's messages (mentioned in #1). When you receive the message WM_CREATE you have to call CreateWindow(). The class is what control is that window, for example "edit" is a text box and "button" is a.. button :). You have to specify an ID for each control (of your choice but unique among all). CreateWindow() returns a handle to that control, which needs to be memorized. When the user clicks on a control you receive the WM_COMMAND message with the ID of that control. Here you can handle that event. You might find useful SetWindowText() and GetWindowText() which allows you to set/get the text of any control.
You will need only the win32 SDK. You can get it here.