Question

I understand EOF and EOL but when I was reading this question (second part of answer) and i got my concepts broken :
Specially the para :

It won’t stop taking input until it finds the end of file(cin uses
stdin, which is treated very much like a file)

so i want to know when we do some thing like in c++ under windows :
std::cin>>int_var; , and we press enter , this end the input but according to reference link it should only stop taking input after hitting ctrl+z.

So i would love to know how std::*stream deal with EOF and EOL.

Second part:
please have a look at this example :

std::cin.getline(char_array_of_size_256 ,256);
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
cout << "artist is " << artist << endl;

If i remove std::cin.ignore() it simply stops taking input (which is known case) but when i keep it , it waits for a new input which is ended by '\n' . But it should simply clear up stream rather then waiting for any new input ending-up with ‘\n’.

Thanks for giving you time)

Answer 1

End-of-line and end-of-file are very different concepts.

End-of-line is really just another input character (or character sequence) that can appear anywhere in an input stream. If you’re reading input one character at a time from a text stream, end-of-line simply means that you’ll see a new-line ('\n') character. Some input routines treat this character specially; for example, it tells getline to stop reading. (Other routines treat ' ' specially; there’s no fundamental difference.)

Different operating systems use different conventions for marking the end of a line. On Linux and other Unix-like systems, the end of a line in a file is marked with a single ASCII linefeed (LF, ‘\n’) character. When reading from a keyboard, both LF and CR are typically mapped to '\n' (try typing either Enter, Control-J, or Control-M). On Windows, the end of a line in a file is marked with a CR–LF pair (\r\n). The C and C++ I/O systems (or the lower-level software they operate on top of) map all these markers to a single '\n' character, so your program doesn’t have to worry about all the possible variations.

End-of-file is not a character, it’s a condition that says there are no more characters available to be read. Different things can trigger this condition. When you’re reading from a disk file, it’s just the physical end of the file. When you’re reading from a keyboard on Windows, control-Z denotes end-of-file; on Unix/Linux, it’s typically control-D (though it can be configured differently).

(You’ll usually have an end-of-line (character sequence) just before end-of-file, but not always; input can sometimes end in an unterminated line, on some systems.)

Different input routines have different ways of indicating that they’ve seen an end-of-file condition. Read the documentation for each one for the details.

As for EOF, that’s a macro defined in <stdio.h> or <cstdio>. It expands to a negative integer constant (typically -1) that’s returned by some functions to indicate that they’ve reached an end-of-file condition.

EDIT: For example, suppose you’re reading from a text file containing two lines:

one
two

Let’s say you’re using C’s getchar(), getc(), or fgetc() function to read one character at a time. The values returned on successive calls will be:

'o', 'n', 'e', '\n', 't', 'w', 'o', '\n', EOF

Or, in numeric form (on a typical system):

111, 110, 101, 10, 116, 119, 111, 10, -1

Each '\n', or 10 (0x0a) is a new-line character read from the file. The final -1 is the value of EOF; this isn’t a character, but an indication that there are no more characters to be read.

Higher-level input routines, like C’s fgets() and C++’s std::cin >> s or std::getline(std::cin, s), are built on top of this mechanism.