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johnny_xing | 14 Oct 2008 12:48

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

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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korfuri | 14 Oct 2008 13:12
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Re : How to call another separate program and passing some variables in C?

2008/10/14, johnny_xing <johnny_xing <at> 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
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-c-programming" in
> the body of a message to majordomo <at> vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

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.
(Continue reading)

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johnny_xing | 15 Oct 2008 08:27

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

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);

Thanks & Best Regards,

Johnny Xing
-----Original Message-----
From: linux-c-programming-owner <at> vger.kernel.org
[mailto:linux-c-programming-owner <at> vger.kernel.org] On Behalf Of
korfuri <at> gmail.com
Sent: 2008年10月14日 19:12
To: johnny_xing
Cc: linux-c-programming <at> vger.kernel.org
(Continue reading)

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johnny_xing | 15 Oct 2008 10:31

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

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,
(Continue reading)

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johnny_xing | 15 Oct 2008 11:10

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

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 <at> gmail.com] 
Sent: 2008年10月15日 16:52
To: johnny_xing
Cc: korfuri <at> gmail.com; linux-c-programming <at> 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:
(Continue reading)

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Per Jessen | 15 Oct 2008 11:05
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Favicon

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

johnny_xing wrote:
> 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
> 

argv[0] is always the name of the called binary.  To get the arguments,
(Continue reading)

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johnny_xing | 15 Oct 2008 11:35

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

Yes that works for me as well.

Thanks a lot guys.

Thanks & Best Regards,

Johnny Xing
________________________________________
From: Halesh S [mailto:halesh.tux <at> gmail.com] 
Sent: 2008年10月15日 17:28
To: johnny_xing
Cc: korfuri <at> gmail.com; linux-c-programming <at> vger.kernel.org
Subject: Re: How to call another separate program and passing some variables in C?

Please check below
argv[0] will have prgram name itself...so its giving 0...
Start from argv[1] :)

Try below, I am able to valid result.

prog1.c
------------
int main()
{
  system("./prog2 1 2 3");
  exit(0);
}

prog2.c
-------------
(Continue reading)

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Jianjun Kong | 16 Oct 2008 02:41
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Re: How to call another separate program and passing some variables in C?

On Wed, Oct 15, 2008 at 05:10:36PM +0800, johnny_xing wrote:
>Hi, Halesh,
>
>Same result as above, I am wondering if system() should be used if we want to pass some arguments as well.

$ man system

You can get more information :)

>Thanks & Best Regards,
> 
>Johnny Xing
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