DaniWeb Forum Index > Software Development > C++

C++ RSS

How to call in the external function?

Please support our C++ advertiser: Intel Parallel Studio Home

Thread Solved

•

Join Date: Jun 2007

Posts: 1,301

Reputation: evstevemd has a spectacular aura about

Solved Threads: 124

evstevemd

Offline

Nearly a Posting Virtuoso

How to call in the external function?

Apr 24th, 2009

I have two files and I would like to call addition function from functions.cpp in main.cpp. But I get error:

In function `int main()':
error: `addition' has both `extern' and initializer
error: initializer expression list treated as compound expression
warning: left-hand operand of comma has no effect
error: `addition' cannot be used as a function|
||=== Build finished: 3 errors, 1 warnings ===|

Here are files
main.cpp

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
 
using namespace std;
 
int main()
{
    int summation;
    int a, b;
    cout <<"Please Enter the two digits to add"<<endl;
    cin>>a>>b;
    //add external f(x) from function.cpp
    extern int addition(a, b);
    summation = addition(a, b);
    cout<<"The sum is "<<summation;
    return 0;
 
}
#include <iostream>

using namespace std;

int main()
{
    int summation;
    int a, b;
    cout <<"Please Enter the two digits to add"<<endl;
    cin>>a>>b;
    //add external f(x) from function.cpp
    extern int addition(a, b);
    summation = addition(a, b);
    cout<<"The sum is "<<summation;
    return 0;

}

functions.cpp

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
int addition(int a, int b)
{
    int sum;
    sum = a+b;
    return(sum);
}
int addition(int a, int b)
{
    int sum;
    sum = a+b;
    return(sum);
}

Atheist: God is man made imagination, he doesn't exist!
Theist: It's okay, can you imagine anything else that doesn't exist?
Junior MD --- Python, C++ and PHP

•

Join Date: Feb 2009

Posts: 1,968

Reputation: tux4life has a reputation beyond repute

Solved Threads: 214

tux4life

Offline

Posting Virtuoso

Re: How to call in the external function?

Apr 24th, 2009

Add extern "C++" int addition(int a, int b); to main.cpp (outside your main function), delete the instruction external int addition(a, b); from inside your main function

...

main.cpp

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
 
using namespace std;
 
// use the external addition function
extern "C++" int addition(int a, int b);
 
int main()
{
    int summation;
    int a, b;
    cout <<"Please Enter the two digits to add"<<endl;
    cin>>a>>b;
    summation = addition(a, b);
    cout<<"The sum is "<<summation;
    return 0;
 
}
#include <iostream>

using namespace std;

// use the external addition function
extern "C++" int addition(int a, int b);

int main()
{
    int summation;
    int a, b;
    cout <<"Please Enter the two digits to add"<<endl;
    cin>>a>>b;
    summation = addition(a, b);
    cout<<"The sum is "<<summation;
    return 0;

}

Now just compile and link them (main.cpp and functions.cpp) togheter ...

Last edited by tux4life; Apr 24th, 2009 at 5:20 pm.

"Never argue with idiots, they just drag you down to their level and then beat you with experience."

•

Join Date: Jun 2007

Posts: 1,301

Reputation: evstevemd has a spectacular aura about

Solved Threads: 124

evstevemd

Offline

Nearly a Posting Virtuoso

Re: How to call in the external function?

Apr 24th, 2009

Great man! I appreciate!

Atheist: God is man made imagination, he doesn't exist!
Theist: It's okay, can you imagine anything else that doesn't exist?
Junior MD --- Python, C++ and PHP