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Need help with #if defined() used with SET environment VARIA

 
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Guest
PostPosted: Sat Mar 17, 2007 11:56 pm    Post subject: Need help with #if defined() used with SET environment VARIA Reply with quote


I'm using bcc32 5.5.1 on WinXP. Can someone help with doing a #if
defined(MY_SET_VAR) test at compile time. MY_SET_VAR is set with SET
MY_SET_VAR=5 from the WinXP command line. I am trying the simple
program:

First, from the command line, I do:

set MY_SET_VAR=5

Then compile:

int main() {

#if defined(MY_SET_VAR)
printf ("MY_SET_VAR"=%i\n", MY_SET_VAR );
#else
printf ("MY_SET_VAR does not exist.\n");
#endif


return 0;
}

Then run and program always prints that MY_SET_VAR does not exist.

I'm working on some programs that suggest this is possible in some
way, but I don't know.

Thanks.
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Ed Mulroy
Guest
PostPosted: Sun Mar 18, 2007 12:17 am    Post subject: Re: Need help with #if defined() used with SET environment V Reply with quote


Quote:
MY_SET_VAR is set with
SET MY_SET_VAR=5 from the WinXP command line

Then MY_SET_VAR is an item in the operating system environment and available
for use on command lines given to the operating system. However C and C++
macros are defined in the program and not in the operating system
environment.

To have it defined in your program put this in the source code prior to
where the macro is used.

#define MY_SET_VAR 5

If writing in C++ doing this instead is an alternative and is in some ways.

const int MY_SET_VAR = 5;

.. Ed

Quote:
irvpaton wrote in message
news:1174157780.807471.246210 (AT) l77g2000hsb (DOT) googlegroups.com...

I'm using bcc32 5.5.1 on WinXP. Can someone help with doing a #if
defined(MY_SET_VAR) test at compile time. MY_SET_VAR is set with SET
MY_SET_VAR=5 from the WinXP command line. I am trying the simple
program:

First, from the command line, I do:

set MY_SET_VAR=5

Then compile:

int main() {

#if defined(MY_SET_VAR)
printf ("MY_SET_VAR"=%i\n", MY_SET_VAR );
#else
printf ("MY_SET_VAR does not exist.\n");
#endif

return 0;
}

Then run and program always prints that MY_SET_VAR does not exist.

I'm working on some programs that suggest this is possible in some
way, but I don't know.
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Michel Leunen
Guest
PostPosted: Sun Mar 18, 2007 1:16 am    Post subject: Re: Need help with #if defined() used with SET environment V Reply with quote


irvpaton (AT) gmail (DOT) com wrote:

Quote:
I'm working on some programs that suggest this is possible in some
way, but I don't know.

Besides what Ed told you, you can try

set MY_SET_VAR=5

and then run this:

#include <iostream>
#include <stdlib.h>
#include <conio.h>

int main(void)
{
if (getenv("MY_SET_VAR")==NULL)
std::cout<<"MY_SET_VAR does not exist.\n"<<std::endl;
else
std::cout<<"MY_SET_VAR="<<getenv("MY_SET_VAR")<<std::endl;

getch();
return 0;
}

Michel
--
----------------------------------------
Michel Leunen
mailto: see my homepage.
C++Builder, BCC5.5.1 Web site:
http://www.leunen.com/
----------------------------------------
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Guest
PostPosted: Sun Mar 18, 2007 10:04 pm    Post subject: Re: Need help with #if defined() used with SET environment V Reply with quote
Thanks both for the good replies. However, I was working with a
prewritten system and it had the #if defined(MY_SET_VAR) to control
things during compile. Someone told me to do this type of thing:

bcc32 -DMY_SET_VAR=5 mycfile.c

which did work.

Irv
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