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looking for function

I'm not student, looking for homework help.

I'm looking for a c function that will execute a system function then
return the output into a string. I don't want to use a file as a medium.
pipe to file , read file and return conntents. I would rather avoid the
file IO.

char* dump;
dump = ex_system("/bin/ls /home/me");

char* ex_system(char* ex)
{
char buf[very_big];
//setup some pipes and fork
//to capture stdout/stderr in buf
exec($ex);
return buf;
}
___ _ ____ ___ __ __
/ _ )(_) / /_ __ / _ \___ _/ /_/ /____ ___
/ _ / / / / // / / ___/ _ `/ __/ __/ _ \/ _ \
/____/_/_/_/\_, / /_/ \_,_/\__/\__/\___/_//_/
/___/
Texas Instruments ASIC Circuit Design Methodlogy Group
Dallas, Texas, 214-480-4455, b-******@ti.com
Nov 14 '05 #1
14 2296
Billy Patton <bp*****@bright .dal.design.ti. com> writes:
I'm looking for a c function that will execute a system function then
return the output into a string. I don't want to use a file as a medium.
pipe to file , read file and return conntents. I would rather avoid the
file IO.


C doesn't have such a function.
--
"For those who want to translate C to Pascal, it may be that a lobotomy
serves your needs better." --M. Ambuhl

"Here are the steps to create a C-to-Turbo-Pascal translator..." --H. Schildt
Nov 14 '05 #2
Billy Patton wrote:
I'm looking for a c function that will execute a system function then
return the output into a string.
There is no such function in Standard C. Your system may have such a
library function, so you could ask on a newsgroup for your system, if
you don't need your program to be portable.
I don't want to use a file as a medium. pipe to file , read file and
return conntents. I would rather avoid the file IO.


Well, it involves file IO, but one fairly common function is the popen()
function. Maybe your system has that. You run a command, and the
output is piped to a C FILE* which you can fread() or whatever and then
pclose(). That way, at least you don't need to create a file in the
file system and delete it afterwards.

--
Hallvard
Nov 14 '05 #3
In article <Pi************ *************** ***@bright.dal. design.ti.com>,
Billy Patton <bp*****@bright .dal.design.ti. com> wrote:
I'm not student, looking for homework help.

I'm looking for a c function that will execute a system function then
return the output into a string. I don't want to use a file as a medium.
pipe to file , read file and return conntents. I would rather avoid the
file IO.

char* dump;
dump = ex_system("/bin/ls /home/me");

char* ex_system(char* ex)
{
char buf[very_big];
//setup some pipes and fork
//to capture stdout/stderr in buf
exec($ex);
return buf;
}


check out http://www.comeaucomputing.com/techtalk/#system
That said, this is highly dependent upon your "environmen t",
and you will pretty much find that you can't find a C function
that'll return such a string and that you probably will need
to use a file, pipe, etc.
--
Greg Comeau/4.3.3:Full C++03 core language + more Windows backends
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?
Nov 14 '05 #4
Billy Patton wrote:
I'm not student, looking for homework help.

I'm looking for a c function that will execute a system function then
return the output into a string. I don't want to use a file as a medium.
pipe to file , read file and return conntents. I would rather avoid the
file IO.

char* dump;
dump = ex_system("/bin/ls /home/me");

char* ex_system(char* ex)
{
char buf[very_big];
//setup some pipes and fork
//to capture stdout/stderr in buf
exec($ex);
return buf;
}


Ick :( Why not just parse the directory using standard system calls from C?

#include <sys/types.h>
#include <dirent.h>

etc.

Look into closedir, close, opendir, readdir, rewinddir, seekdir, telldir
and scandir.

Good luck.

--James
_______________ _______________ ____
A random quote of nothing:

QOTD:
"When she hauled ass, it took three trips."

Nov 14 '05 #5
On Wed, 17 Dec 2003 08:37:58 +1100, Centurion <sp*******@nowh ere.com>
wrote:
Ick :( Why not just parse the directory using standard system calls from C?

#include <sys/types.h>
#include <dirent.h>

etc.

Look into closedir, close, opendir, readdir, rewinddir, seekdir, telldir
and scandir.


Because none of the above are "standard system calls", and neither of
the headers you specify are standard.

--
Al Balmer
Balmer Consulting
re************* ***********@att .net
Nov 14 '05 #6
Any particular reason you set followups out of comp.lang.c? (I'm trying
to refrain from making rude comments about being unable to handle
correction from the CLC regulars.)

In article <oi***********@ gandalf.grayonl ine.id.au>,
Centurion <sp*******@nowh ere.com> wrote:
Ick :( Why not just parse the directory using standard system calls from C?

#include <sys/types.h>
#include <dirent.h>

etc.

Look into closedir, close, opendir, readdir, rewinddir, seekdir, telldir
and scandir.


Perhaps because none of these are standard system calls from C?

They look pretty posixish to me. The appropriate newsgroup for that,
as I believe has already been pointed out, is comp.unix.progr ammer .
dave

--
Dave Vandervies dj******@csclub .uwaterloo.ca
Think of it as rocket science: the failures are _much_ more educational than
the launches in which everything goes like clockwork and without error.
--Mike Andrews in the scary devil monastery
Nov 14 '05 #7
Centurion <sp*******@nowh ere.com> writes:
Ick :( Why not just parse the directory using standard system calls from C?
C doesn't have "standard system calls", nor does it have a
concept of "directorie s".
#include <sys/types.h>
#include <dirent.h>
These are not standard C header files.
Look into closedir, close, opendir, readdir, rewinddir, seekdir, telldir
and scandir.


None of these are standard C functions.
--
"I should killfile you where you stand, worthless human." --Kaz
Nov 14 '05 #8
In article <09************ *************** *****@4ax.com>,
al******@att.ne t says...

[ ... ]
Because none of the above are "standard system calls", and neither of
the headers you specify are standard.


I normally don't nitpick over grammar, but this thread has had some many
examples of this error that I can't stand it any more. "None" is
singular, and so is "neither", so your sentence above should read
something like this:

Because none of the above is a "standard system call" and
neither of the headers you specify is standard."

Now back to your regularly scheduled flaming...

--
Later,
Jerry.

The universe is a figment of its own imagination.
Nov 14 '05 #9
Jerry Coffin wrote:
In article <09************ *************** *****@4ax.com>,
al******@att.ne t says...

[ ... ]
Because none of the above are "standard system calls", and neither of
the headers you specify are standard.


I normally don't nitpick over grammar, but this thread has had some many
examples of this error that I can't stand it any more. "None" is
singular, and so is "neither", so your sentence above should read
something like this:

Because none of the above is a "standard system call" and
neither of the headers you specify is standard."


You are mistaken. "None" is not necessarily singular. Here's what
"Fowler's Modern English Usage" has to say:

none. 1 It is a mistake to suppose that the pronoun is singular
only and must at all costs be followed by singular verbs or
pronouns. It should be borne in mind that /none/ is not a
shortening of /no one/ but is the regular descendant of OE nan
(pronoun) `none, not one'. At all times since the reign of King
Alfred the choice of plural or singular in the accompanying
verbs, etc., has been governed by the surrounding words or by
the notional sense. Some examples will clarify matters:

[numerous examples elided]

Verdict: use a singular verb where possible but if the notion of
plurality is present a plural verb has been optional since the
OE period and in some circumstances is desirable. The type
/None of them have finished their essays/ is better than the
clumsy ... /has finished his or her essay/.

Jeremy.
Nov 14 '05 #10

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