Technical facts

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

IDE(s):

Qt Creator 3.1.1

Project type:

Console application

C++ standard:

C++98

Compiler(s):

G++ 4.9.2

Libraries used:

STL: GNU ISO C++ Library, version 4.9.2

Qt project file: ./CppStdEqualExample2/CppStdEqualExample2.pro


include(../../ConsoleApplication.pri) #Or use the code below

# QT += core

# QT += gui

# greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

# CONFIG   += console

# CONFIG   -= app_bundle

# TEMPLATE = app

# CONFIG(release, debug|release) {

#   DEFINES += NDEBUG NTRACE_BILDERBIKKEL

# }

# QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra -Weffc++

# unix {

#   QMAKE_CXXFLAGS += -Werror

# }



include(../../Libraries/Boost.pri) #Or use the code below

# win32 {

#   INCLUDEPATH += \

#     ../../Libraries/boost_1_54_0

# }



SOURCES += main.cpp

./CppStdEqualExample2/main.cpp


#include <algorithm>

#include <cassert>

#include <set>

#include <vector>



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <boost/shared_ptr.hpp>

#pragma GCC diagnostic pop



const std::vector<boost::shared_ptr<int>> Create(const int n)

{

  assert(n >= 0);

  std::vector<boost::shared_ptr<int>> v;

  for (int i=0; i!=n; ++i)

  {

    const boost::shared_ptr<int> p(new int(i));

    v.push_back(p);

  }

  return v;

}



int main()

{

  //Compare two identical std::vectors: prefer operator!=

  {

    const std::vector<boost::shared_ptr<int>> v { Create(2) };

    const std::vector<boost::shared_ptr<int>> w { Create(2) };



    //Mismatch: compares the memory addresses of the integers

    assert(v != w);

    //Less preferred, no unexpected behaviour

    assert(!std::equal(v.begin(),v.end(),w.begin()));

  }

  //Compare two identical std::vectors: prefer operator!=

  {

    const std::vector<boost::shared_ptr<int>> v { Create(2) };

    std::vector<boost::shared_ptr<int>> w(v);



    //Match: compares the memory addresses of the integers

    assert(v == w);

    //Less preferred, no unexpected behaviour

    assert(std::equal(v.begin(),v.end(),w.begin()));



    std::swap(*w.begin(),*(w.end()-1));



    assert(v != w);

    //Less preferred, no unexpected behaviour

    assert(!std::equal(v.begin(),v.end(),w.begin()));

  }

  //Compare two different containers

  {

    const std::vector<boost::shared_ptr<int>> v { Create(2) };

    std::set<boost::shared_ptr<int>> w(v.begin(),v.end());



    //Less preferred, no unexpected behaviour

    assert( (     std::equal(v.begin(),v.end(),w.begin())

              || !std::equal(v.begin(),v.end(),w.begin()) )

      && "Unknown if the shared_ptrs are allocated in memory at incremental adresses"

    );

  }

}

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

This page has been created by the tool CodeToHtml

(C++) StdEqualExample2

Technical facts

Qt project file: ./CppStdEqualExample2/CppStdEqualExample2.pro

./CppStdEqualExample2/main.cpp