c - `getchar()` gives the same output as the input string

Question

I am confused by a program mentioned in K&R that uses getchar(). It gives the same output as the input string:

#include <stdio.h>

main(){
    int c;
    c = getchar();
    while(c != EOF){
         putchar(c);
         c = getchar();
    }
}

Why does it print the whole string? I would expect it to read a character and ask again for the input.

And, are all strings we enter terminated by an EOF?

Answer 1

In the simple setup you are likely using, getchar works with buffered input, so you have to press enter before getchar gets anything to read. Strings are not terminated by EOF; in fact, EOF is not really a character, but a magic value that indicates the end of the file. But EOF is not part of the string read. It's what getchar returns when there is nothing left to read.