Stumped by K&R exercise 1.5.2

Question

I am currently trying to learn C by using the K&R, but I am completely stumped by example 1.5.2. For some reason, after I press Ctrl-Z, instead of printing nc, it prints nc multiplied by 2. I don't know what could be causing this problem (I copied the code exactly how it is in the book). The compiler I am using is Visual Studio 2010. Here is the code:

#include <stdio.h>

main()
{

long nc;

nc = 0;
while (getchar() != EOF)
    ++nc;
printf("%1d\n", nc);


}

I assume you mean "it prints 2", not "nc multiplied by 2". I guess the Ctrl+Z is generating 2 keystrokes. — Nick Shaw, Sep 18 '11 at 06:31
oh, I see now, so that is why every keystroke was registering twice instead of once. — Emryss, Sep 18 '11 at 06:33
possible duplicate of [Why do I require multiple EOF (CTRL+Z) characters?](http://stackoverflow.com/questions/5655112/why-do-i-require-multiple-eof-ctrlz-characters) — Foo Bah, Sep 18 '11 at 06:36
@Foo - that has nothing to do with it. He was properly hitting ^Z on its own. — Brian Roach, Sep 18 '11 at 06:37

Brian Roach · Accepted Answer · 2011-09-18T06:41:26.757

2

Because enter is a keystroke.

If your input is:

1<enter>
1<enter>
1<enter>
^z

it would output:

6

edited Sep 18 '11 at 06:41

answered Sep 18 '11 at 06:35

Brian Roach

76,169
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score 1 · Answer 2 · answered Sep 18 '11 at 06:32

1

Not sure why you get the behaviour you describe but that should be %ld not %1d

answered Sep 18 '11 at 06:32

Tom

43,583
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score 0 · Answer 3 · answered Sep 18 '11 at 06:40

Could not reproduce your error. I added some debugging statements,

#include <stdio.h>

main() {
     int nc = 0, ch;

     while ((ch = getchar()) != EOF) {
          printf("%d\n", ch);
          ++nc;
     }
     printf("nc - %1d\n", nc);


}

And then tried it with gcc on Windows:

E:\temp>gcc eof.c

E:\temp>a
^Z
nc - 0

E:\temp>a
foo bar
102
111
111
32
98
97
114
10
^Z
nc - 8

And then with Visual Studio 2008:

E:\temp>cl eof.c
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 15.00.30729.01 for 80x86
Copyright (C) Microsoft Corporation.  All rights reserved.

eof.c
Microsoft (R) Incremental Linker Version 9.00.30729.01
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:eof.exe
eof.obj

E:\temp>eof
^Z
nc - 0

E:\temp>eof
foo bar
102
111
111
32
98
97
114
10
^Z
nc - 8

He was hitting `enter` after each letter he typed (resulting in `nc` being twice as large as he expected). See comments. — Brian Roach, Sep 18 '11 at 06:45

Stumped by K&R exercise 1.5.2

3 Answers3