c++ problem with build

Question

I have this method declaration in Util.h file

 30:string to_string(const bit_vector& v);

Util.cc file has the definition

 string to_string(const bit_vector& v){
 string str = "";
  for (bit_vector::const_iterator i = v.begin(); i < v.end(); ++i){
    if(*i == 1) str += "1";
    else str += "0";
  }
  return str;
}

when I try to build the project it says that in line 30

error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C2143: syntax error : missing ',' before '&'

Im using visual studio 2008, Can some one help me to get out of these two errors! Dont know whether there is a problem with bit_vector !!! any ideas???

Answer 1

I'd also look at lines before it. The compiler clearly isn't considering bit_vector to be a type in this declaration, so yes the problem could be in the bit_vector declaration.

Answer 2

From the error message it seems like when uitl.h is being processed by the compiler it has no idea what a bit_vector is.

You'll need to make sure that whatever header declares bit_vector is included before that point. You can either include the header for bit_vector in util.h or you can add an appropriate forward declaration:

class bit_vector;

Answer 3

It seems bit_vector is not defined. There are claims that it should be included in <vector>, but that doesn't seem to be the case on Visual Studio 2008. Try

typedef vector<bool> bit_vector;

before the first usage of bit_vector.

Answer 4

May be compiler does not know what is string. Write

using std::string;

Answer 5

Visual Studio 2008 doesn't define bit_vector by default.

In the header file it has the following:

#if _HAS_TRADITIONAL_STL
 typedef _Bvector bit_vector;
 #define __vector__ vector
#endif /* _HAS_TRADITIONAL_STL */

But _HAS_TRADITIONAL_STL doesn't seemed to be defined by default.

Its definition of _Bvector is:

typedef vector<bool, allocator<bool> > _Bvector;

So you can either #define _HAS_TRADITIONAL_STL before including <vector> or just use vector<bool, allocator<bool>> directly.

Answer 6

bit_vector isn't part of the C++ standard library. It's part of some older non-standard STL implementations though...

SGI's STL documentation of bit_vector says:

Warning: The name bit_vector will be removed in a future release of the STL...not defined in the C++ standard, and is retained only for backward compatibility.

And the only thing on MSDN is a forum post by on of the VC++ developers:

bit_vector is not an official part of the C++ Standard and hence is not part of the Visual C++ release.

I certainly wouldn't use #define _HAS_TRADITIONAL_STL - it's undocumented and may well disappear in future versions of the Microsoft compiler.