C++ linker error

I have a file A.cpp which has the following lines:

#include"B.h"
int main(int argc, char **argv)
{
  ...
  char *input_file = *argv;  
  B *definition = new B(input_file);
  ...
}

In B.h, I have the following:

class B
{
  public:
   // Constructors
   B(void);
   B(const c开发者_如何学编程har *filename);
   ...
}

When I compile, I get the following error: undefined reference to 'B::B(char const*)'

Any suggestions on how to fix?

Thanks.

---

You need a definition for B::B(char const *). You have provided only a declaration for B::B(char const *), and the Linker is complaining that it can't actually find that function.

---

It seems like you specified the header for the function, but never actually wrote the body of the function.

You need to define the function I.E.

B::B(const char *filename){
  // Do stuff
}

in B.cpp.

Your problem doesn't have anything to do with const correctness.