RE: How to call another separate program and passing some variables in C?

["johnny_xing" <johnny_xing@banshing.com>]

Hi, Halesh,

Same result as above, I am wondering if system() should be used if we want to pass some arguments as well.

Thanks & Best Regards,
 
Johnny Xing
 
________________________________________
From: Halesh S [mailto:halesh.tux@gmail.com] 
Sent: 2008年10月15日 16:52
To: johnny_xing
Cc: korfuri@gmail.com; linux-c-programming@vger.kernel.org
Subject: Re: How to call another separate program and passing some variables in C?

Try program 2 as below, no need to use sprintf

In program 2:
int main(int argc, char *argv[])
{
int input1;
printf("buffer is %s\n", argv[0]);
input1 =atoi(argv[0]);
printf("input1 value is %d\n",input1);
}
Halesh



Try program 2 as below, no need to use sprintf

In program 2:
int main(int argc, char *argv[])
{
int input1;
char buffer[10];
printf("buffer is %s\n", buffer);
input1 =atoi(buffer);
printf("input1 value is %d\n",input1);
}
 - Halesh 

2008/10/15 johnny_xing <johnny_xing@banshing.com>
2008/10/15 johnny_xing <johnny_xing@banshing.com>
Hi,
 
I tried as what Hlalesh said and it doesn't work.
 
Here is what I have:
 
In program 1:
 
system("/usr/local/src/program2 1");
 
In program 2:
int main(int argc, char *argv[])
{
int input1;
char buffer[10];
sprintf(buffer, argv[0]);
 
printf("buffer is %s\n", buffer);
input1 =atoi(buffer);
printf("input1 value is %d\n",input1);
}
 
The output is:
 
buffer is /usr/local/src/parallel/asterisk
input1 value is 0
 
 
Anything wrong with it?
 
 
Thanks & Best Regards,
 
Johnny Xing
 
________________________________________
From: Halesh S [mailto:halesh.tux@gmail.com] 
Sent: 2008年10月15日 14:34
To: johnny_xing
Cc: korfuri@gmail.com; linux-c-programming@vger.kernel.org

Subject: Re: How to call another separate program and passing some variables in C?
 
 
2008/10/15 johnny_xing <johnny_xing@banshing.com>
Hi, Uriel

Yes I need to execute two separate programs although I know it would be much
easier if I could put into one program.

The reason is the first program invokes lots of other modules and program
and it has been fixed and running that I don't know how to add in the second
program.

However, if I could invoke the second program using system() and pass some
integers to the second program to generate the output I want, it will be
good enough.

Eg: system("/usr/local/src/program2");

The problem is I don't know how to pass some integers upon invoking it.

Is it something like this if I want to pass an integer 1?
system("/usr/local/src/program2" 1);

  Use system("/usr/local/src/program2 1");

  the argument will stored as string in *argv[] in 2nd prog.
  Convert back to integer using sprintf / any of ur own method.

 Halesh
  


Thanks & Best Regards,

Johnny Xing
-----Original Message-----
From: linux-c-programming-owner@vger.kernel.org
[mailto:linux-c-programming-owner@vger.kernel.org] On Behalf Of
korfuri@gmail.com
Sent: 2008年10月14日 19:12
To: johnny_xing
Cc: linux-c-programming@vger.kernel.org
Subject: Re : How to call another separate program and passing some
variables in C?

2008/10/14, johnny_xing <johnny_xing@banshing.com>:
> Hi,
>
> Forgive me if my question is so simple as I am a newbie to programming..
>
> I have two C programming and I want to call second C file within my first
C
> program, upon calling, I need to pass some variables (like 1 or 0) to the
> second program.
>
> Can anyone tell me how to do? I searched system() but it seems not be able
> to do this.
>
> Thanks & Best Regards,
>
> Johnny
>
>
> --
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>

Hi,

You can use system() if you build the command-line (e.g. with
sprintf()) to pass the arguments you want. Then you can access it in
your 2nd program with argc/argv.

An alternative is to use fork() and execve(). Please note that you
have to convert each argument to a string so execve() can use it. Here
again you can use sprintf() for this purpose.

But are you sure you need two separate programs ? You can build 2 C
files together into one binary. That makes passing variables much
easier as it results to a normal function call.

Hope this will help
Regards,
Uriel

--
Uriel "Korfuri" Corfa
Epitech student
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