What is meant by console input and output in C language?

Answer 1

A console is simply another term for a computer terminal. All computer terminals have input and output devices but as console programmers we don't always have the luxury of knowing the specific details about those devices. All we can say for sure about any input or output device is that those devices are character streams. That is, we can extract characters from an input device and we can insert characters into an output device.

Most console programs accept input via a keyboard and present output upon a screen or monitor, however it is never safe to assume that that will always be the case. This is because console programs have two global devices known as standard input and standard output (stdin and stdout, respectively). If we make use of either of these devices then we can never really be certain what physical devices are attached to them because the user must always be free to decide that for themselves. However, because all console input and output devices are character streams, it really doesn't matter what physical devices are used, we can treat them all exactly the same.

A lot of new programmers often make the mistake of enforcing specific devices upon the standard input and output streams, but this is one of those cases where just because we can do something it doesn't mean that we should. Standard input/output devices must always be user-defined, never programmer-enforced.

A console program can make use of as many input and output devices as it needs in addition to the standard input and output devices. Thus if a program needs to extract information from a specific disk file then it is free to do so -- there is no need to redirect standard input to that file.