asked on

finctions in a lib...

Hi,
I want to make a dll with +- the following two functions (It's a sample problem to point out what I want. I know that the following code is dumb)
-------------------------------------
void f1(int i)
{
int j =5 + i;
}

void f2()
{
\\here I want to do stj with int j, which is defined in f1
}
--------------------------------------
is this possible ??
How should I do this?? (I know allready how to make really simple dll's)

pb_india

you will have to make j variable global or declare it in the beginning before definging f1() and f2()

pb_india

//Example

int j=0;

void f1(int i)
{
j =5 + i;
}

void f2()
{
j=f1(10)+5;

}

AzizLight

ASKER

Thanks, but what if the j is calculated (I think you can't place code (not-initialisation) out of functions for making a dll, isn't that correct) ??

AzizLight

ASKER

I'm trying to compile the code for the following dll and got these errors:
code:
--------
#include "dlltest.h"
#define MAXMODULE 50
char module[MAXMODULE];

extern "C" __declspec(dllexport)
void f1()
{int k = 22;
cout << "f1"<<endl;
}

extern "C" __declspec(dllexport)
void f2()
{cout << "f2 : " << k <<endl;
}
--------------
error:
'k' : undeclared identifier
...

rstaveley

Forget about DLLs for a bit. Your error message is simply telling you that k can't be seen from f2. Its scope is limited to f1.

pb_india

Use this:
You cannot declare "k" in one function and use in another. You have to make it globally available as below:

#include "dlltest.h"
#define MAXMODULE 50

char module[MAXMODULE];
int k=0;
extern "C" __declspec(dllexport)
void f1()
{
k = 22;
cout << "f1"<<endl;
}

extern "C" __declspec(dllexport)
void f2()
{
cout << "f2 : " << k <<endl;
}

rstaveley

Follow pb_india's recommendation if you want k's scope to span all functions in the module.

AzizLight

ASKER

Thanks, both,
but to come back to my question above.... (sorry if I'm nagging)
what if the j is calculated (I think you can't place code (not-initialisation) out of functions for making a dll, isn't that correct) ??
I know that you can first initialise everything global, and the make a function CalculateAtInitialisation(initialised data) or sth like that, but I have lots of variables to initialise, so it would be nice if there is a keyword or something like that that can make that youre data is also available for other functions....

pb_india

You can use a class and declare variable as private.
Then you can write "get" and "set" functions to access the variable.
That way the data will be availabe to all functions.

I don;t celarly understand what you mean here:
what if the j is calculated (I think you can't place code (not-initialisation) out of functions for making a dll, isn't that correct) ??

You can certainly have code out side functions.

AzizLight

ASKER

"You can certainly have code out side functions." yes, but for a dll you don't have a main loop (which is also a function, actually (?!)), so where should you place the "global code" ??

thanks.

ASKER CERTIFIED SOLUTION

pb_india

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AzizLight

ASKER

Hi,
could you perhaps give some sample (pseudo)code of a dll-cpp-file where there are some calculations done in the "initialisation" function??
(sorry I'm so dumb ...)

rstaveley

Points to pb_india though he didn't respond to the follow-on question.