Books about C often refer to “input streams” and “output streams.” A stream is a sequence of bytes flowing into the program (input) or flowing out (output). The data might have originally come from the keyboard, a modem, a disk file, or some other peripheral device. The outgoing data might be sent out to the screen, a modem, or a disk file.
Thus, when you see a phrase such as “opening a stream,” it means opening a line of communication to the disk drive or to some other peripheral.
Summary: Peripherals and files are called “streams” in C.
The five streams always open and available for DOS input or output are shown in Table 11.1.
Table 11.1 Standard I/O Streams
| Name | Stream |
| stdin | Standard input (keyboard) |
| stdout | Standard output (screen) |
| stderr | Standard error channel (screen) |
| stdprn | Standard printer (parallel port) |
| stdaux | Standard auxiliary device (serial) |
NOTE:
QuickWin programs do not support the stdprn and stdaux streams.