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Global Variables help

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Join Date: Aug 2004

Posts: 140

Reputation: Mahen is an unknown quantity at this point

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Mahen

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Junior Poster

Global Variables help

Aug 7th, 2005

Suppose i have a main.cpp file and a test.h file:
///////////////////////////////////////////
//main.cpp

#include <iostream.h>
#include <string.h>
void test();

char foo[200];
int main()
{
strcpy(foo, "testing");
test();
return 0;
}
//////////////////////////////////////////////////////////////
//test.h

void test()
{
cout << mir << endl;
}

WHY IS "mir" AN UNDECLARED IDENTIFIER

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Join Date: Feb 2005

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winbatch

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Posting Pro in Training

Re: Global Variables help

Aug 7th, 2005

This has nothing to do with global variables, you simply never defined what mir is. (what data type)

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Join Date: Jul 2005

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Sauce

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Re: Global Variables help

Aug 9th, 2005

And unless i'm mistaken, you forgot

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 #include "test.h"

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Join Date: Aug 2004

Posts: 140

Reputation: Mahen is an unknown quantity at this point

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Mahen

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Re: Global Variables help

Aug 9th, 2005

Am sorry but i left many mistakes, undertand me, i typed this quickly without passing tru a compiler. I WAS RUNNING OUT OF TIME
HERE IS THE CORRECTED CODE:

Suppose i have a main.cpp file and a test.h file:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
///////////////////////////////////////////
//main.cpp
 
#include <iostream.h>
#include <string.h>
#include "test.h"
 
void test();
 
char mir[200];
int main()
{
strcpy(mir, "testing");
test();
return 0;
}
///////////////////////////////////////////
//main.cpp

#include <iostream.h>
#include <string.h>
#include "test.h"

void test();

char mir[200];
int main()
{
strcpy(mir, "testing");
test();
return 0;
}

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
//////////////////////////////////////////////////////////////
//test.h
 
void test()
{
cout << mir << endl;
}
//////////////////////////////////////////////////////////////
//test.h

void test()
{
cout << mir << endl;
}

<< moderator edit: added [code][/code] tags >>

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Join Date: Jul 2005

Posts: 55

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Sauce

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Junior Poster in Training

Re: Global Variables help

Aug 9th, 2005

You are still not declaring mir in the test.h file. When you are using a variable in C and it is declared in a different file you have to declare it again using the "extern" keyword to let the compiler know that the variable is declared else where, so try...

main.c (using C code instead of C++)

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 C Syntax (Toggle Plain Text) 
#include "test.h"
 
char mir[200]="testing";
 
int main()
{
      test();
      return 0;
}
#include "test.h"

char mir[200]="testing";

int main()
{
      test();
      return 0;
}

test.h

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 C Syntax (Toggle Plain Text) 
void test()
{
     extern char mir[200];
     printf("%s\n, mir);
}
 
void test()
{
     extern char mir[200];
     printf("%s\n, mir);
}

My compiler was complaining about my iostream.h file so i just used the printf instead and omitted the need for string.h but initializing the char array when i declared it.