Shared variables

[Disruptive]

Hi

Am having a bit of trouble with variables not updating when they should when they are declared with the extern keyword. I have taken an example from the web to try this out and still it does not work. Do you have any idea where this is going wrong.

I keep getting the old values and the new values never appear. The variables are there, but for some reason when I change their initial value, this is never reflected in the code. Is there a memory issue here?

Failing this is there anyway of getting variables across several files easily and elegantly?

Thanks

/*----------------------------------------------------------------------------
VARS.H

Note: #define VAR_DECLS 1 before including this file to DECLARE and INITIALIZE
global variables. Include this file without defining VAR_DECLS to extern
these variables.
----------------------------------------------------------------------------*/
#ifndef CNF_DEFS // Make sure this file is included only once
#define CNF_DEFS 1

/*----------------------------------------------
Setup variable declaration macros.
----------------------------------------------*/
#undef CNF_DECLS
#ifndef CNF_DECLS
# define _DECL extern
# define _INIT(x)
#else
# define _DECL
# define _INIT(x) = x
#endif

/*----------------------------------------------
Declare variables as follows:

_DECL [standard variable declaration] _INIT(x);

where x is the value with which to initialize
the variable. If there is no initial value for
the varialbe, it may be declared as follows:

_DECL [standard variable declaration];
----------------------------------------------*/

_DECL int Xsections _INIT(5);
_DECL int Ysections _INIT(5);
_DECL int Zsections _INIT(5);
_DECL int MaxLipidsinCell _INIT(40);
_DECL double PI _INIT(3.14159);
_DECL int LipidTotal _INIT(9);
_DECL int Beads _INIT(2);
_DECL double sigma _INIT(1.0);

#endif
/*----------------------------------------------------------------------------
----------------------------------------------------------------------------*/





and the .cpp file:


#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <string.h>
#include <stdio.h>
#include <iostream.h>
#include <fstream.h>


#define CNF_DECLS
#include "Vars.h"
//#include "Sorts.h"






int main(void)
{

int myarray[Beads][LipidTotal];
int myarrayEnd[Beads];
int TotalArray[LipidTotal];
int TotalArrayEnd;
int duplicates;


myarray[0][0] = 0;
myarray[0][1] = 134;
myarray[0][2] = 1423;
myarray[0][3] = 1323;
myarray[0][4] = 121;
myarray[0][5] = 13;
myarray[0][6] = 1321;
myarray[0][7] = 112;
myarray[0][8] = 12;
myarrayEnd[0] = 9;
myarrayEnd[1] = 9;
myarray[1][0] = 0;
myarray[1][1] = 0;
myarray[1][2] = 0;
myarray[1][3] = 0;
myarray[1][4] = 0;
myarray[1][5] = 0;
myarray[1][6] = 0;
myarray[1][7] = 0;
myarray[1][8] = 0;

printf("Lipid %d\n",LipidTotal);
// AddListsTogether(TotalArray,TotalArrayEnd,myarray,myarrayEnd);
for (int i=0;i<(TotalArrayEnd);i++)
{
//printf("before [%d]: %d\n",i,TotalArray);

}


}

 

[cpjust]

The only extern variables that I see being used in main() are LipidTotal and Beads. Neither of them appear to be assigned any values. I also don't see where they are defined - I just see them declared in Vars.h.

 

[Disruptive]

They should be declared automatically as they are included and declared, Look at the #define portion. The variables are most certainly assigned. However their value cannot be changed on susequent compile and run.

 

[cpjust]

Oh I see now, you #define CNF_DECLS before you include Vars.h, in which case they are assigned a value but not extern... But I still don't see where you are changing their values.
These are the only places I see the global variables being referenced:

 int myarray[Beads][LipidTotal];
 int myarrayEnd[Beads];
 int TotalArray[LipidTotal];
...
printf("Lipid %d\n",LipidTotal);

 

[Disruptive]

Here is the website from where I obtained the example. I still dont find that is works. Try it out and then change the initial variables declared.

http://www.keil.com/support/docs/1868.htm

 

[Salem]

I agree with cpjust, you need to show where you're trying to modify those globals, not just a few snippets of commented out code.

Oh, and that macro trickery is really tacky IMO.


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