What is "conio.h"

conio.h is a C header file used mostly by MS-DOS compilers to provide console input/output. It is not part of the C standard library or ISO C, nor is it defined by POSIX.

This header declares several useful library functions for performing "console input and output" from a program. Most C compilers that target DOS, Windows 3.x, Phar Lap, DOSX, OS/2, or Win32 have this header and supply the associated library functions in the default C library. Most C compilers that target UNIX and Linux do not have this header and do not supply the library functions. Some embedded systems use a conio-compatible library.

The library functions declared by conio.h vary somewhat different from compiler to compiler. As originally implemented in Lattice C, the various functions mapped directly to the first few DOS INT 21H functions. The library supplied with Borland's Turbo C did not use the DOS API but instead accessed video RAM directly for output and used BIOS interrupt calls. This library also has additional functions inspired from the successful Turbo Pascal one.

Compilers that target non-DOS operating systems, such as Linux or OS/2, provide similar solutions; the unix-related curses library is very common here. Another example is SyncTERM's ciolib. The version of conio.h done by DJ Delorie for the GO32 extender is particularly extensive.

• kbhit - Determines if a keyboard key was pressed.
• getch - Reads a character directly from the console without buffer, and without echo.
• getche - Reads a character directly from the console without buffer, but with echo.
• ungetch - Puts the character c back into the keyboard buffers.
• cgets - Reads a string directly from the console.
• cscanf - Reads formatted values directly from the console.
• putch - Writes a character directly to the console.
• cputs - Writes a string directly to the console.
• cprintf - Formats values and writes them directly to the console.
• clrscr - Clears the screen.