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C++ static member linker problem

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Started by tasen February 01, 2008 06:40 AM

5 comments, last by tasen 16 years, 2 months ago

tasen

148

Author

February 01, 2008 06:40 AM

Hi all, I'm having trouble with the following: foo.h

#ifndef FOO_H
#define FOO_H

#include <string>

class Foo {
public:
  typedef std::string StringType;

  // ...

  static const StringType default;
private:
  // ...
};

#endif

foo.cpp

#include "foo.h"

const Foo::StringType default = Foo::StringType();

main.cpp

#include "foo.h"

int main()
{
  Foo::StringType s = "foo";

  if (s == Foo::default)
    s = "bar";
}

Trying to compile this (on MSVC++ 2008 Express) gives the following linker errors: 1>main.obj : error LNK2001: unresolved external symbol "public: static class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const Foo::default" (?st@Foo@@2V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@B) 1>C:\Documents and Settings\d\Desktop\foo\Debug\foo.exe : fatal error LNK1120: 1 unresolved externals I can't seem to figure out what the problem is; if anyone can help me out I'd greatly appreciate it.

ToohrVyk

1,596

February 01, 2008 06:44 AM

Is foo.cpp compiled and linked with the rest of the program?

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SiCrane

11,840

February 01, 2008 07:08 AM

How on earth does that compile? Using a keyword as a variable name should blow up in half a dozen ways before it even hits the link stage.

ToohrVyk

1,596

February 01, 2008 07:28 AM

Visual C++ 2005 seems to only treat "default" as a keyword if it's followed by a colon, even with the language extensions disabled. Apparently, so does the 2008 version.

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bakery2k1

712

February 01, 2008 07:32 AM

Quote:

const Foo::StringType default = Foo::StringType();

You want:

const Foo::StringType Foo::default = Foo::StringType();

phear-

162

February 01, 2008 10:50 AM

Isn't "default" a reserved word that you cant use?

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tasen

148

Author

February 01, 2008 05:27 PM

Quote:Original post by ToohrVyk
Is foo.cpp compiled and linked with the rest of the program?

Yes.

Quote:Original post by SiCrane
How on earth does that compile? Using a keyword as a variable name should blow up in half a dozen ways before it even hits the link stage.

Sorry, that wasn't actually what the variable was called in my program, I changed it to try and make the example a bit more clear (forgetting that it actually is a keyword!). However, just for fun I changed it to default and strangely enough it compiles. o_O

Quote:Original post by ToohrVyk
Visual C++ 2005 seems to only treat "default" as a keyword if it's followed by a colon, even with the language extensions disabled. Apparently, so does the 2008 version.

That's correct.

Quote:Original post by bakery2k1
You want:

const Foo::StringType Foo::default = Foo::StringType();

Thanks. That's exactly what I needed.

C++ static member linker problem

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C++ static member linker problem

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