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Input and Output Methods

There are two different approaches to console I/O, the choice of which depends on how much flexibility and control an application needs. The high-level approach enables simple character stream I/O, but it limits access to a console's input and screen buffers. The low-level approach requires that developers write more code and choose among a greater range of functions, but it also gives an application more flexibility.

An application can use the file I/O functions, ReadFile and WriteFile, and the console functions, ReadConsole and WriteConsole, for high-level I/O that provides indirect access to a console's input and screen buffers. The high-level input functions filter and process the data in a console's input buffer to return input as a stream of characters, discarding mouse and buffer-resizing input. Similarly, the high-level output functions write a stream of characters that are displayed at the current cursor location in a screen buffer. An application controls the way these functions work by setting a console's I/O modes.

The low-level I/O functions provide direct access to a console's input and screen buffers, enabling an application to access mouse and buffer-resizing input events and extended information for keyboard events. Low-level output functions enable an application to read from or write to a specified number of consecutive character cells in a screen buffer, or to read or write to rectangular blocks of character cells at a specified location in a screen buffer. A console's input modes affect low-level input by enabling the application to determine whether mouse and buffer-resizing events are placed in the input buffer. A console's output modes have no effect on low-level output.

The high-level and low-level I/O methods are not mutually exclusive, and an application can use any combination of these functions. Typically, however, an application uses one approach or the other exclusively.

The following topics describe the console modes and the high-level and low-level I/O functions.

 

 

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