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ykarj

some problems I need help with

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this code is inside "decs.h"
      
#ifndef DECS_H
#define DECS_H

#define WIN32_LEAN_AND_MEAN
#include < windows.h >
#include < iostream >
#include < fstream >

using namespace std;

class someClass {
private:
int x;
int y;

public:
someClass() { } 
~someClass() { }

friend ostream operator<<(ostream &stream, someClass c);
// inserter for the class 

};

extern ofstream log("my.log");

#endif // DECS_H  

    

this code is inside "inserter.cpp":
      
#include "decs.h"

ostream operator<<(ostream &stream, someClass c) {
stream << "class info" << endl;

return stream;
}  
  
this code is inside "main.cpp":
      
#include "decs.h"

int WINAPI WinMain(HINSTANCE hInstance, 
HINSTANCE hPrevInstance, 
LPSTR lpCmdLine, 
int nCmdShow) {
someClass c;

log << c;

return 0;
}
    
I have 2 problems with this code: 1. the linker throws an error saying the log variable is already defind in main.obj when linking inserter.obj why? is it because every time I include decs.h a variable is created? doesnt the extern modifier make it global to all files? 2. if I solve the first problem by moving the variable log to main.cpp (which is not a good solution since I want to use it all over the project), another problem arises: the overloaded operator doesnt have access to private members of someClass. again, Why? doesnt the friend modifier take care of that? hope it's clear enough.. btw: if anyone suggests a new subject for the topic i'd be glad to change it! Edited by - ykarj on December 13, 2001 2:32:37 PM

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a) You can''t initialize an ''extern'' variable : you''re doing a declaration, not a definition. Leave ''extern ofstream log;'' in the header and put ''ofstream log("my.log")'' in a cpp file.

b) The exact prototype for ''operator<<()'' on streams is ''ostream& operator<<(ostream&, const YourType& );''. The ''friend'' declaration should work though.

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off the top of my head, i would say the first problem could be solved by using:

extern ofstream log;

in your header and:


ofstream log( "mylog.txt" );

in only ONE of the source files.



crazy166
some people think i''m crazy, some people know i am

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thanks guys, i''ll try to remove the initialization from the header file.

fruny: I have tried the operator declaration with and without the ''&''. the function just can''t access the private vars of the class for some reason.

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well, I removed the inititlization from the header file and it now works fine.

the problem with the friend function not being able to access provate members of the class still stands, so if anyone has any idea..

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