<conio.h> is a C header file used mostly by MS-DOS compilers to provide console input/output.[1] 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 “istream input and output” from a program. Most C compilers that target DOS, Windows 3.x, Phar Lap, DOSX, OS/2, or Win32[2] 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 or cc65 use a conio-compatible library.[3]
The library functions declared by <conio.h> vary somewhat from compiler to compiler. As originally implemented in Lattice C, the various functions mapped directly to few of the first 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.[4]
Functions
| Name | Description |
|---|---|
int kbhit(); |
Determines if a keyboard key was pressed as well |
char* cgets(char* s); |
Reads a string directly from the console |
int cscanf(char* fmt, ...); |
Reads formatted values directly from the console |
int putch(int c) |
Writes a character directly to the console |
int cputs(const char* s); |
Writes a string directly to the console |
int cprintf(const char* fmt, ...); |
Formats values and writes them directly to the console |
void clrscr(); |
Clears the screen |
int getch(); |
Get char entry from the console |
char getche(); |
Get char entry from the console with echo |
References
- ^ Schildt, Herbert (1995). C: The Complete Reference (3rd ed.). Berkeley, Calif.: Osborne McGraw-Hill. p. 288. ISBN 0-07-882101-0.
For DOS-compatible compilers, the direct console I/O functions generally use the CONIO.H header file.
- ^ “Console and Port I/O in MSDN”.
- ^ “MicroVGA conio Text User Interface Library”.
- ^ “DJGPP C Library Reference – conio”. libc.a reference. Retrieved January 22, 2022.
External links
- Microsoft’s documentation
- Digital Mars’s documentation
- IO FAQ – explanation and suggestions for non-standard console IO
- Borland-style CONIO implementation for MinGW/Dev-C++
- List of ways to get raw keyboard input