TITLE: No type-safety based upon externals

[ Material adapted from "C++ Gotchas", tutorial notes by 
  Tom Cargill, p. 8]

Consider the following two files, which have mismatched
external declarations:

(main.cc)

	#include <iostream.h>

	extern long key;
	extern char* msg;

	int main ()
	{
		cout << "key = " << key << endl;
		msg += 8;
		*msg = 'O';
		cout << "msg = " << msg << endl;
		return 0;
	}

(misc.cc)

	#include <iostream.h>

	short key = 43;

	const char* const msg = "cannot touch!";

Executing this test program might result in the following
output:

	key = 245839
	msg = Ouch!