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On Jul 21, 10:29*pm, Malcolm McLean <malcolm.mcle...@btinternet.com>
wrote:
> On Jul 21, 10:35*pm, happytoday <ehabaziz2...@gmail.com> wrote:> It wasrequired to remove empty lines using C program . Either to be
> > run like :
>
> > ./nnoemptylines < textfile
>
> > or accept location of the file as a full path from the user dialog to
> > accept .
>
> The spec is almost impossible.
>

FWIW, while the point you make below is valid, I doubt if that is what
the OP intended.



> ./noemptylines < textfile redirects textfile to stdin. So if the
> program is invoked thusly, it needs to read in lines from stdin, check
> if they are non-blank, and then echo them to stdout. So far so good.
> The problem is that
> ./noemptyfiles
>
> should set up a dialogue with the user. So you want to print something
> like
> "Hello user, please enter the name of the file from which ypu wish to
> remove blanks"
> The user enters
> textfile
> "Thank you, do you wish to overwrite the file?"
>
> etc
>
> The problem is that there's no easy way to know whether stdin is
> directed from a file or coming from a keyboard. That's deliberate. We
> don't generally want programs making this distinction. I'm sure that
> on your particular system there will besome operating call, probably
> poorly documented, which you can make. But it's inappropriate and bad
> practice to use it for a ultility program like a deblanker.
>

POSIX provides a 'isatty()' that allows programs to make such a
distinction.


- Anand

On Jul 21, 8:07*pm, Keith Thompson <ks...@mib.org> wrote:
> happytoday <ehabaziz2...@gmail.com> writes:
> > It was required to remove empty lines using C program . Either to be
> > run like :
>
> > ./nnoemptylines < textfile
>
> > or accept location of the file as a full path from the user dialog to
> > accept .
>
> One common answer to questions like this is to ask the questioner
> to supply the e-mail address of his or her instructor, so we can
> submit our solutions directly.
>
> --
> Keith Thompson (The_Other_Keith) ks...@mib.org *<http://www.ghoti.net/~kst>
> Nokia
> "We must do something. *This is something. *Therefore, we must do this."
> * * -- Antony Jay and Jonathan Lynn, "Yes Minister"

Haha... I like that

"happytoday" <> wrote in message
news:dd3fce00-b8a2-4758-9184-...
> It was required to remove empty lines using C program . Either to be
> run like :
>
> ./nnoemptylines < textfile
>
>
> or accept location of the file as a full path from the user dialog to
> accept .

Haven't written any C for a while, tried this:

#include <stdio.h>
#include <stdlib.h>

int main(int nargs, char** args) {
FILE *infile,*outfile;
int c,lastc='\n';

if (nargs<2) {
infile=stdin;
puts("(Reading from stdin)");
}
else {
infile=fopen(args[1],"r");
if (infile==0) {
printf("Can't find %s\n",args[1]);
exit(0);
}
printf("(Reading from %s\n",args[1]);
}
outfile=stdout;

while(1) {
c=fgetc(infile);
if (c==EOF) break;
if (c!='\n' || lastc!='\n') fputc(c,outfile);
lastc=c;
}

if (infile==stdin) fclose(infile);
if (outfile==stdout) fclose(outfile);

}

This sends output to stdout, rather than overwrite the input file (which is
tricky to do, as well as being a bad idea unless a backup scheme is in
place).

--
Bartc

On 22 Jul., 03:30, gaze...@shell.xmission.com (Kenny McCormack) wrote:
> And when you do post code, it (*) will just get worse.
>
> (*) The abuse and misleading advice.
>
> --
> (This discussion group is about C, ...)
>
> Wrong. *It is only OCCASIONALLY a discussion group
> about C; mostly, like most "discussion" groups, it is
> off-topic Rorsharch [sic] revelations of the childhood
> traumas of the participants...

You really hit the spot.

I could easily proof your theory by suggesting Seed7.


Greetings Thomas Mertes

--
Seed7 Homepage: http://seed7.sourceforge.net
Seed7 - The extensible programming language: User defined statements
and operators, abstract data types, templates without special
syntax, OO with interfaces and multiple dispatch, statically typed,
interpreted or compiled, portable, runs under linux/unix/windows.