(C++) StdEnable_ifExample1

 

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: ./CppStdEnable_ifExample1/CppStdEnable_ifExample1.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

 

 

 

 

 

./CppStdEnable_ifExample1/main.cpp

 

---

//Adapted from http://www.cplusplus.com/reference/type_traits/enable_if // enable_if example: two ways of using enable_if #include <iostream> #include <type_traits> // 1. the return type (bool) is only valid if T is an integral type: template <class T> typename std::enable_if<   std::is_integral<T>::value,bool>::type   is_odd(const T i) {   return static_cast<bool>(i%2); } // 2. the second template argument is only valid if T is an integral type: template <class T,   class = typename std::enable_if<std::is_integral<T>::value>::type> bool is_even (T i) {   return !static_cast<bool>(i%2); } int main() {   const int i = 1; //code does not compile if type of i is not integral   std::cout     << "i is odd : " << is_odd(i) << '\n'     << "i is even: " << is_even(i) << '\n'; }