char ch;
int count = 0;
std::cin.get(ch);
while (!std::cin.eof()) {
std::cout << ch;
count++;
std::cin.get(ch);
}
std::cout << '\n' << count << " characters read\n";some text here
some text here
eof
eof
^D
Процесс завершился c кодом выхода 0
Saying that Ctrl-D sends EOF is an educational lie-to-children. What it actually does is make any ongoing read() from the terminal return immediately with the contents of the current line buffer if any.
Synergy happens because the Unix convention is that a read() of zero bytes represents EOF.
This means that if you press Ctrl-D with an empty buffer, the read() will return with zero bytes, and a canonical program will interpret it as end-of-file. This is obviously just an illusion since you're still there to input more on the terminal, and a less canonical program could just keep reading if it wanted to.
If you instead press Ctrl-D after entering some data, then that data is just returned and a canonical program will keep reading to find a linefeed or whatever else it's looking for.
This is why EOF behavior is only triggered in canonical programs when Ctrl-D is pressed either after another Ctrl-D (the first flushes the buffer, the second returns a now-empty buffer) or after an Enter (for the same reason).
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