Port Input/Output
| Function | Header File | Description |
| _inp | conio.h builtin.h |
Reads a byte value from a specified input port. |
| _inpd | conio.h builtin.h |
Reads a 4-byte value from a specified input port. |
| _inpw | conio.h builtin.h |
Reads a 2-byte value from a specified input port. |
| _outp | conio.h builtin.h |
Writes a byte value to a specified output port. |
| _outpd | conio.h builtin.h |
Writes a 4-byte value to a specified output port. |
| _outpw | conio.h builtin.h |
Writes a 2-byte value to a specified output port. |
| umask | io.h | Sets the file permission mask of the executing process environment. |
Character and String Input/Output
| Function | Header File | Description |
| _cgets | conio.h | Reads a string from the keyboard into locations given by arguments. |
| _cprintf | conio.h | Formats and sends a series of characters and values to the screen. |
| _cputs | conio.h | Writes a string directly to the screen. |
| _cscanf | conio.h | Reads data from the keyboard into locations given by arguments. |
| _getch | conio.h | Reads a single character from the keyboard. |
| _getche | conio.h | Reads a single character from the keyboard and displays it. |
| _kbhit | conio.h | Tests if a key has been pressed on the keyboard. |
| _putch | conio.h | Writes a character to the screen. |
| _ungetch | conio.h | Pushes a character back to the keyboard. |
Direct Input/Output
| Function | Header File | Description |
| read | io.h | Reads bytes from a file into a buffer. |
| write | io.h | Writes bytes from a buffer into a file. |
File Positioning
| Function | Header File | Description |
| __eof | io.h | Determines whether the file pointer has reached the end of the file. |
| _tell | io.h | Gets the current position of a file pointer. |
File Access
| Function | Header File | Description |
| access | io.h | Determines whether the given file exists and whether you can gain access to it. |
| chmod | io.h | Changes the permission setting of a file. |
| close | io.h | Closes a file associated with the handle. |
| creat | io.h | Creates a new file or opens and truncates an existing file. |
| dup | io.h | Associates a second file handle with an open file. |
| dup2 | io.h | Associates a second file handle, with possibly different attributes, with an open file. |
| isatty | io.h | Determines whether the handle is associated with a character device. |
| open | io.h | Opens a file and prepares it for subsequent reading and writing. |
| _sopen | io.h | Opens a file and prepares it for subsequent shared reading or writing. |
File Operations
| Function | Header File | Description |
| _chsize | io.h | Lengthens or cuts off the file to a specified length. |
| _filelength | io.h | Returns the length of a file. |
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Alphabetical Listing of IBM C and C++
Compilers Functions and Macros