Re: How to use the istream and ostream?

From:
Ulrich Eckhardt <eckhardt@satorlaser.com>
Newsgroups:
microsoft.public.vc.language
Date:
Thu, 03 Aug 2006 08:47:39 +0200
Message-ID:
<gpi8q3-ltj.ln1@satorlaser.homedns.org>
Ma Xiaoming wrote:

#include <iostream>

istream& operator>>( istream&, String& );
ostream& operator<<( ostream&, const String& );

class String;

class String {

[...]

  bool operator==( const String& );
  bool operator==( const char* );


const? Consider making those (friend) functions instead so you can overload
for const char* on the left side, too.

  int size() { return _size; }


size_t? const?

  char* c_str() { return _string; }


const?

[...]

    When I include this header file in my project and compile the project
with VC++ 7.0 which was in Visual Studio .NET 2003, the two lines would
cause error:

    istream& operator>>( istream&, String& );
    ostream& operator<<( ostream&, const String& );


Just a suggestion for the future: remove everything else that is not needed
to demonstrate the problem. You have in fact two problems here:

- 'istream' and 'ostream' are not types, you mean 'std::istream'
and 'std::ostream'.
- 'String' is not a known type at that time. You could fix that by moving
the declaration ("class String;") to before these two lines.

Uli

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