Access a variable declared in one file in anothe file in VC++. (Extern keyword usage)

Question

I have a VC++ solution (using VS2008) with 2 projects Project A & project B.

Everything I discuss below is wrt Project A.

Project A has a sourec file a.cpp & it includes a header file "a.h". "a.h" has a variable int varA; which is modifies inside a.cpp.

a.cpp: int varA = x*2; // also do some calculations with varA in a.cpp

Now there is one more sourec file b.cpp in the same project A. And now lets say this "b.cpp" also includes same header file "a.h". i.e

b.cpp int varB = varA; // If I want to access varA & get the current value of varA here in b.cpp what should do ? Will it work if I declare varA as extern in a.h & include

Here it's important to note that I wnat to not only access the variable varA from within b.cpp but also want to access the current value of this variable as updated by a.cpp.

Thnaks in advance.

Do you mean you want to access the variable varA in b.cpp after it has been modified in a.cpp? — Alok Save
– Alok Save, Commented May 25, 2012 at 6:25

Sudhakar B · Accepted Answer · 2012-05-25 06:37:12Z

2

Create a header file A.h

extern int varA;

In A.cpp declare variable

int varA;

Include "A.h" in b.cpp

That's it.

answered May 25, 2012 at 6:37

Sudhakar B

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Paskas · Accepted Answer · 2012-05-25 06:32:46Z

Declare variable in some header file and then include this header to cpp file where you want to use it.

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