c++header

"std_lib_facilities.h" showing error


I am using Codeblocks 17.12 and have already set compiler settings to C++11 standard. I am studying from Bjarne Stroustrup's book "Programming - Principles and Practice using C++". In his book he asked to include "std_lib_facilities.h". I copied it from his website and saved in "include" folder of "Mingw" folder. After that I proceeded to make a simple program:

#include<iostream>
#include "std_lib_facilities.h"
main()
{
    std::cout<<"Hello world";
}

But the compiler is showing following errors and warnings:

 warning: This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date.  
 Please use a non-deprecated interface with equivalent functionality instead. 
 For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated. [-Wcpp]

 error: template-id 'do_get<>' for 'String > 
   std::__cxx11::messages<char>::do_get(std::messages_base::catalog, int, int, const String&) const' does not match any template declaration

 note: saw 1 'template<>', need 2 for specializing a member function template

Also the error which is showing is in the 1971 line of the header file "locale_facets_nonio.h".
I tried to find out the solution to this problem in other forums, but could not find a satisfactory answer.
Some are saying we should not use this file "std_lib_facilities.h" at all as it is using deprecated or antiquated headers.


Solution

  • we should not use this file "std_lib_facilities.h" at all as it is using deprecated or antiquated headers.

    You should #include standard headers as you use them. The std_lib_facilities.h might get out of sync.

    #include<iostream>
    #include "std_lib_facilities.h"
    int main() {
        std::cout<<"Hello world";
    }
    

    should rather be

    #include<iostream>
    // #include "std_lib_facilities.h" Remove this entirely!
    int main() {
        std::cout<<"Hello world";
    }
    

    Using more standard features like std::string should be:

    #include<iostream>
    #include<string>
    int main() {
        std::string hello = "Hello world";
        std::cout<<hello;
    }
    

    Extending further, reading the #include std_lib_facilities.h in your books example should probably become to expand the actually necessary standard header includes for your compilable and productive code.
    Here's just a default starting template as used by Coliru

    #include <iostream>
    #include <vector>
    
    template<typename T>
    std::ostream& operator<<(std::ostream& os, const std::vector<T>& vec)
    {
        for (auto& el : vec)
        {
            os << el << ' ';
        }
        return os;
    }
    
    int main()
    {
        std::vector<std::string> vec = {
            "Hello", "from", "GCC", __VERSION__, "!" 
        };
        std::cout << vec << std::endl;
    }
    

    Sure you could gather up the

    #include <iostream>
    #include <vector>
    

    in a separate header file, but that would be tedious to keep in sync of what you need in particular with all of your translation units.


    Another related Q&A:

    Why should I not #include <bits/stdc++.h>?