Issue getting `boost::filesystem::path` character pointer

Question

Of the two following lines, the first one gives me a compile time error, the second is fine:

    std::remove( boost::filesystem::path( mypath / "file.log" ).c_str() );
    std::remove( boost::filesystem::path( mypath / "file.log" ).string().c_str() );

The std::remove signature is: int remove( const char* fname );

This is the error message:

"No instance of overloaded function "std::remove" matches the argument list"

But both boost::filesystem::path::c_str() and std::string::c_str() return a const char*.

The compiler I am using is Visual C++ 2013.

Answer 1

But both boost::filesystem::path::c_str() and std::string::c_str() return a const char*

no, this is not true.

We can open boost\filesystem\path.hpp source code and see what is going on there:

  template< typename Char, Char Separator, Char PreferredSeparator, Char Dot >
  struct path_constants
  {
    typedef path_constants< Char, Separator, PreferredSeparator, Dot > path_constants_base;
    typedef Char                                    value_type; // <---
    //...
  };

  class path :
    public filesystem::path_detail::path_constants<
#ifdef BOOST_WINDOWS_API
      wchar_t, L'/', L'\\', L'.'  // [1]
#else
      char, '/', '/', '.'
#endif
    >
  {

and in [1] line wchar_t is passed as first argument Char to path_constants template, so under Windows c_str returns pointer to wide character (2 bytes).