Windows has many features that the standard MS-DOS environment does not. For this reason, Windows applications may, at first, seem more complex than standard MS-DOS applications. This is understandable when you consider some of the additional features that Windows offers:
A graphical user interface featuring windows, menus, dialog boxes, and controls for applications
Queued input
Device-independent graphics
Multitasking capabilities
Data interchange between applications
When writing applications for the MS-DOS environment, most C programmers use the standard C run-time libraries to carry out an application's input, output, memory management, and other activities. The C run-time libraries are for the programmer who is working in a standard operating environment consisting of a character-based terminal for user input and output, and exclusive access to system memory as well as to the input and output devices of the computer.
In Windows, these characteristics are no longer valid. Windows applications share the computer's resources, including the CPU, with other applications. Windows applications interact with the user through a graphics-based screen, a keyboard, and a mouse.