Can you declare a pointer as extern in C ++?

Question

I have the following bit of legacy C ++ code that won't compile:

#include <stdio.h>
#include <iostream>

extern ostream *debug;

GCC (g ++) complains: "expected initializer before" * token "

Looking around, it seems more common to declare them as external links, for example:

extern ostream& debug;

Why is the pointer invalid but the link is in this situation?

DECISION:

The real problem, as mentioned below, is the lack of the std :: namespace specifier. Apparently this was common in older C ++ code.

+1

postfuturist Dec 14. '08 at 3:34 am

1 answer

Johannes Schaub - litb · Accepted Answer · 2008-12-14T03:35:42+0000

Yes, you can declare a pointer using extern. Your mistake, most likely you forgot to qualify with std::

:

// note the header is cstdio in C++. stdio.h is deprecated
#include <cstdio>
#include <iostream>

extern std::ostream *debug;