scanf(), ungetc() behaviour.

[Argento]

I was curious at the start about how ungetc() returns the character to the
stream, so i did the following coding. Things work as expected except if I
change the scanf("%c",&j) to scanf("%d",&j). I don't understand how could
scanf() affect the content of i[0] and i[1]. Can someone tell me why?

#include <stdio.h>
#include <ctype.h>

void main()
{
char i[2], j;
printf("Please input a two digit number:");
i[0]= getchar();
i[1]= getchar();
ungetc(i[1],stdin);
ungetc(i[0],stdin);
scanf("%c", &j); //scanf("%d",&j);
fflush(stdin);
printf("\nYou entered %d in decimal and %c in character mode for
i[0]",i[0],i[0]);
printf("\nYou entered %d in decimal and %c in character mode for
i[1]",i[1],i[1]);
printf("\nYou entered %d in decimal and %c in character mode for j",j,j);

getchar();

}

[Argento]

Well, I have taken to cutting things back to the first few glaring
errors, such as #include <conio.h> or void main(), and ignoring the
rest (assuming I decide to answer at all). After all, one needs to
fix the earliest errors first, all else may well be spurious. This
also reduces the bandwidth wastage.

After so a few replies to me, i have understand about the problem with
void main() but i do not have much idea about <conio.h> other then its
not in the standard. Is there any other problem related to it other then its
not in the stardard/less portable?

[Argento]

Publish the instructors email address here and we will collectively
set him/her right. It is not right to warp the minds of the
innocent.

Are you serious about this? Before you answer that first question, I
would just want you to know, those course books are from OUHK
(Open University of Hong Kong, that's where I currently study about this)
taken from the course code MT258.

[Argento]

(You mean fflush(stdin), of course.) Before deciding whether to burn the
book, however, please ensure that it is not merely using them as examples
of common errors to be avoided.

Definitely not. It's used in almost every-little-single code, lol.

[Argento]

The reason for doing it yourself is that you get to test for
closing errors, and then you can decide what, if any, remedial
steps to take. This may be crucial in avoiding data loss.

Yes, yes, error checking *-)
Because I am just at Unit 5 of the course, there ain't much error
checking idea in my mind yet. Thanks, very informative.

[Vladimir S. Oka]

Argento wrote:

Well, I have taken to cutting things back to the first few glaring
errors, such as #include <conio.h> or void main(), and ignoring the
rest (assuming I decide to answer at all). After all, one needs to
fix the earliest errors first, all else may well be spurious. This
also reduces the bandwidth wastage.

After so a few replies to me, i have understand about the problem with
void main() but i do not have much idea about <conio.h> other then its
not in the standard. Is there any other problem related to it other
then its not in the stardard/less portable?

Please do not remove attribution lines when quoting. It's imporatnat to
know who said what, as well.

As for conio.h, there's nothing wrong with it as such (AFAIK). It's just
that it's implementation and system specific and thus off topic here.
If you have questions about it, they're better answered in one of the
Borland or MS-DOS groups (if my memory serves, but look it up
yourself).

The only possible thing "wrong" with conio.h is that as soon as it's in
your program, it (your program) becomes non-portable, which in these
parts is considered a Bad Thing.

--
BR, Vladimir

We are experiencing system trouble -- do not adjust your terminal.

[Vladimir S. Oka]

Argento wrote:

The reason for doing it yourself is that you get to test for
closing errors, and then you can decide what, if any, remedial
steps to take. This may be crucial in avoiding data loss.

Yes, yes, error checking *-)
Because I am just at Unit 5 of the course, there ain't much error
checking idea in my mind yet. Thanks, very informative.

You're around 4 units late in starting error checking... ;-)

(don't snip attributions)

--
BR, Vladimir

Loose bits sink chips.

[Vladimir S. Oka]

Argento wrote:

Publish the instructors email address here and we will collectively
set him/her right. It is not right to warp the minds of the
innocent.

Are you serious about this? Before you answer that first question, I
would just want you to know, those course books are from OUHK
(Open University of Hong Kong, that's where I currently study about
this) taken from the course code MT258.

In my experience, collective mind of c.l.c regulars trumps your (or any)
University or course books.

(attributions please)

--
BR, Vladimir

At a contest for farting in Butte
One lady's exertion was cute :
It won the diploma
For fetid aroma,
And three judges were felled by the brute.

[Vladimir S. Oka]

Argento wrote:

(You mean fflush(stdin), of course.) Before deciding whether to burn
the book, however, please ensure that it is not merely using them as
examples of common errors to be avoided.

Definitely not. It's used in almost every-little-single code, lol.

Can I watch them burn? ;-)

--
BR, Vladimir

Very few profundities can be expressed in less than 80 characters.

[Argento]

"Vladimir S. Oka" <no****@btopenw orld.com> wrote in message
news:du******** **@nwrdmz01.dmz .ncs.ea.ibs-infra.bt.com...

Please do not remove attribution lines when quoting. It's imporatnat to
know who said what, as well.

As for conio.h, there's nothing wrong with it as such (AFAIK). It's just
that it's implementation and system specific and thus off topic here.
If you have questions about it, they're better answered in one of the
Borland or MS-DOS groups (if my memory serves, but look it up
yourself).

The only possible thing "wrong" with conio.h is that as soon as it's in
your program, it (your program) becomes non-portable, which in these
parts is considered a Bad Thing.

Thanks. I had been reading this newsgroup like a month and only starting
from
yesterday, do i post. Sorry for removing the attribution lines and snip
thing, I use
to roam about in the local newsgroups (Hong Kong, that's where I live), they
have
different manners. They do top-posting and quote the whole thing. I guess I
got
lots to learn from all of you other then C questions.

[Vladimir S. Oka]

Argento wrote:

"Vladimir S. Oka" <no****@btopenw orld.com> wrote in message
news:du******** **@nwrdmz01.dmz .ncs.ea.ibs-infra.bt.com...

Please do not remove attribution lines when quoting. It's imporatnat
to know who said what, as well.

As for conio.h, there's nothing wrong with it as such (AFAIK). It's
just that it's implementation and system specific and thus off topic
here. If you have questions about it, they're better answered in one
of the Borland or MS-DOS groups (if my memory serves, but look it up
yourself).

The only possible thing "wrong" with conio.h is that as soon as it's
in your program, it (your program) becomes non-portable, which in
these parts is considered a Bad Thing.

Thanks. I had been reading this newsgroup like a month and only
starting from
yesterday, do i post. Sorry for removing the attribution lines and
snip thing, I use
to roam about in the local newsgroups (Hong Kong, that's where I
live), they have
different manners. They do top-posting and quote the whole thing. I
guess I got
lots to learn from all of you other then C questions.

Every group has it's own customs. In brief, here you don't top-post,
don't remove attributions, and try to snip stuff that's not relevant,
while leaving enough context. The last one may be difficult, so not
doing it is normally not commented upon (unless you quote a whole 100+
line post with little benefit). Also, your replies should be
interspersed with the quoted text if it makes it clearer to what part
of the post you're replying to. There are also rules on topicality, but
these are better learned by lurking.

Anyway, thanks for taking an interest in learning local customs.

PS
Asbestos underware may also come in handy. ;-)

--
BR, Vladimir

I read Playboy for the same reason I read National Geographic.
To see the sights I'm never going to visit.