Help with getchar() please

geraneum · 11-26-2008, 08:30 AM

HI

I've just started to learn C and C++.

I write the code below but dont get desired answer. I want to count the characters but when I run it and type something, a new line begins and nothing happen...

Code:

#include <stdio.h>

main()
{
	int nc;

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

I'm compiling with Borland CodGear in Windows...

Thanks

cmnorton · 11-26-2008, 08:43 AM

Look for The EOF pitfall

http://en.wikipedia.org/wiki/Fopen

Hko · 11-26-2008, 09:21 AM

While cmnorton's link is probably a good read and the EOF pitfall is certainly a thing to keep in mind, your code is OK in that respect.

I would recommend changing the printf statement a little though:

Code:

printf("%d\n",nc);

The solution to your 'problem' is quite simple: your code is waiting (looping) until a End-Of-File (EOF) comes in from the standard input. And by pressing enter, you're not sending a EOF, but newline character.

Try pressing CTRL-d after typing a few characters. CTRL-d is the way to send EOF.

Or pipe some data from a file or commandline into your program. This will send EOF automatically:

Code:

shell$ cat /etc/fstab | ./yourprog
shell$ echo '123456' | ./yourprog

cmnorton · 11-26-2008, 01:34 PM

Quote:

Originally Posted by Hko

While cmnorton's link is probably a good read and the EOF pitfall is certainly a thing to keep in mind, your code is OK in that respect.

I would recommend changing the printf statement a little though:

Code:

printf("%d\n",nc);

The solution to your 'problem' is quite simple: your code is waiting (looping) until a End-Of-File (EOF) comes in from the standard input. And by pressing enter, you're not sending a EOF, but newline character.

Try pressing CTRL-d after typing a few characters. CTRL-d is the way to send EOF.

Or pipe some data from a file or commandline into your program. This will send EOF automatically:

Code:

shell$ cat /etc/fstab | ./yourprog
shell$ echo '123456' | ./yourprog

Thanks. I forgot about generating a CTRL-D on stdin.

geraneum · 11-27-2008, 11:48 AM

I understood your explanation.
I've thought about it that process is still in the loop. cause any code after the loop didn't execute. But I didn't know why...
Thank you even if I can't get result I know the solution now.

But when I write something in input and press Ctrl-D nothing happen but something like this: hello^D...

Thanks

Hko · 11-27-2008, 12:41 PM

Quote:

Originally Posted by geraneum

But when I write something in input and press Ctrl-D nothing happen but something like this: hello^D...

You need to have at least one newline (i.e.: press enter) before ctrl-d. Or pressing ctrl-d twice also worked on my computer, but then the number is printed right after the string I typed.

If that does not work, then your terminal (or shell?) probably does no recognize ctrl-d as EOF. Try another terminal (or shell?) (bash, xterm, konsole, whatever...)

geraneum · 11-29-2008, 10:55 AM

I've found it just now...
http://www.mhuffman.com/notes/dos/bash_cmd.htm

Hko · 11-30-2008, 01:32 PM

ah,yes. I totally overlooked it was under Windows. Sorry.

baig · 12-01-2008, 04:24 AM

you have used getchar..

but from where you are getting those chars???

no file pointer present in your code..

define a file pointer to your file.. e.g

FILE *fp;

fp=fopen("yourfile","r");

while( fp!=EOF)
{

bla bla...

}

Hko · 12-18-2008, 04:42 AM

Quote:

Originally Posted by baig

you have used getchar..

but from where you are getting those chars???

From the standard input one would suspect..