Question

I am reading PrenticeHall. The C Programming Language – 2nd Ed.Kernighan,Ritchie.

In this book(pg-20) an example of a program is given which is supposed to print the number of characters that user types in the console window, and here is its code .

#include <stdio.h>

main()
{
    double nc;
    for (nc = 0; getchar() != EOF; ++nc)
        ;

    printf("%.0f\n", nc);
}

But when I run this , and type something in the console, it wont print anything at all, the cursor would keep on blinking .
and this is exactly the way code is written in that book.

I have tried it another way also, but this also didn’t work out, same result as that previous code.

#include <stdio.h>

main()
{
    long nc;
    nc = 0;
    while (getchar() != EOF)
            ++nc;

    printf("%ld\n", nc);
}

any ideas to how to make this thing work ?

P.S.
I am using windows OS. (still)

Answer 1

The reason is that the code tries to read all the input until the end of file. If this program was reading from a file, it would know when it ended, but since it’s reading from console, you have to explicitly tell it that the input is over. On Linux you do this by pressing ^D (Ctrl+D), on Windows ^Z (Ctrl+Z).

Note that it has to be done at the start of a new line, i.e. after pressing Enter, you press ^D (^Z on Win).

I am reading PrenticeHall. The Ansi C Programming Language – 2nd
Ed.Kernighan,Ritchie.

That’s a very good book you’re reading. It’s that good, I guess, it contains the answer to your question.