Is printf supposed to print out a 'long' value?

Question

Possible Duplicate:
Why doesn’t getchar() recognise return as EOF in windows console?

I'm trying to print out the value in the variable 'nc' in the next program:

int main()

{ 
 long nc;
 nc = 0;

 while (getchar() != EOF)
 ++nc;
 printf("%ld\n", nc); 
}

Please tell me why is it not printing?

"Not printing"? I just tried running your code and it works as expected. What are you using as input for your program? — AnT stands with Russia, Jan 11 '13 at 21:01
@user1959174: In that case, why do you expect your program to print anything, if you never end the `while` loop? — AnT stands with Russia, Jan 11 '13 at 21:02
hi @AndreyT it was my bad, i didn't realize that until you guys mention my problem here. I only started learning C 2 days ago. — MNY, Jan 11 '13 at 21:21

Inisheer · Accepted Answer · 2013-01-11T21:27:42.540

5

You don't have brackets in your while loop (this is why not using brackets leads to error prone software). Therefore, the value is getting incremented, but not printing.

Try:

int main(int argc, char** argv)
{ 
    long nc;
    nc = 0;

    while (getchar() != EOF)
    { // ADD THIS
        ++nc;
        printf("%ld\n", nc); 
    } // AND THIS
}

otherwise, your code is essentially doing:

int main(int argc, char** argv)
{ 
    long nc;
    nc = 0;

    while (getchar() != EOF)
    {
        ++nc; // ENDLESSLY ADDING
    }
    printf("%ld\n", nc); // NEVER REACHED DUE TO WHILE LOOP.
}

edited Jan 11 '13 at 21:27

answered Jan 11 '13 at 21:04

Inisheer

20,376
9
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too bad there is no feature that you can add certain people that help you in the past to future question :) @Inisheer – MNY Jan 11 '13 at 21:30
@user1959174 Maybe, but I could certainly see that getting out of hand as well :P . – Inisheer Jan 11 '13 at 21:31
hah yes i know, this is probably the reason they didnt do it in the first place. I'm sure they though of that @Inisheer . tell me buddy, I just recently started to learn programming and took C as the first language cause people recomanded me that if I want to learn Objective -C, it will be good o have a solid understanding of C. I started couple of days ago with the book "the c programming language" (k&r), do you think its a good book for programming beginners? – MNY Jan 11 '13 at 21:34
@user1959174 See here for good recommendations: http://stackoverflow.com/questions/562303/the-definitive-c-book-guide-and-list?rq=1 – Inisheer Jan 12 '13 at 14:29

score 3 · Answer 2 · answered Jan 11 '13 at 21:01

Your while loop will continue to loop until you end the input using Control-D on Unix or Control-Z, Return on Windows. It will do this without printing anything because you did not use braces around the ++nc and printf.

You may also have problems with printf if you did not #include <stdio.h> at the top of your program. If the compiler does not know that printf is a varargs function, it will not format the argument list correctly when calling it.

score 3 · Answer 3 · answered Jan 11 '13 at 21:07

3

after entering some inputs like

1 2 4 u must type ctrl + D since its the EOF ASCII equivalent.

Else modify the progeam and put

while(getchar()!='\r') (until you hit Enter)

answered Jan 11 '13 at 21:07

Sagar Sakre

2,336
22
31

score 1 · Answer 4 · answered Jan 11 '13 at 21:01

1

What do you mean? It works:

./a.out 
asdfsdfasdfasdfasddddddddddddddddddddddd
41

echo "Try to count this" | ./a.out 
18

answered Jan 11 '13 at 21:01

Eddy_Em

864
6
14

MOHAMED · Answer 5 · 2013-03-18T08:53:46.510

1

you have to stop reading characters from stdin by stopping the while loop of getchar

and then you will see the nc value printed

To do

EOF = CTRL + D (for Linux)

EOF = CTRL + Z (for Windows)

edited Mar 18 '13 at 08:53

answered Jan 11 '13 at 21:01

MOHAMED

41,599
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Is printf supposed to print out a 'long' value?

5 Answers5