(C++) Dynamic_castExample1

 

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: ./CppDynamic_castExample1/CppDynamic_castExample1.pro

 

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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 # } SOURCES += main.cpp

 

 

 

 

 

./CppDynamic_castExample1/main.cpp

 

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#include <cassert> struct Base {   virtual ~Base() {} }; struct Derived : public Base { }; int main() {   //Base initialized with derived, can be downcasted to derived   {     Base * const p1 = new Derived;     Derived * const p2 = dynamic_cast<Derived*>(p1);     assert(p1);     assert(p2);     assert(p1 == p2);     delete p1;     //delete p2; //Do not re-delete!   }   //Base initialized with base, cannot be downcasted to derived   {     Base * const p1 = new Base;     Derived * const p2 = dynamic_cast<Derived*>(p1);     assert( p1);     assert(!p2);     assert(p1 != p2);     delete p1;   }   //Const base initialized with derived, can be downcasted to const derived   {     Base * const p1 = new Derived;     const Derived * const p2 = dynamic_cast<const Derived*>(p1);     assert(p1);     assert(p2);     assert(p1 == p2);     delete p1;     //delete p2; //Do not re-delete!   }   //Const base initialized with base, cannot be downcasted to const derived   {     const Base * const p1 = new Base;     const Derived * const p2 = dynamic_cast<const Derived*>(p1);     assert( p1);     assert(!p2);     assert(p1 != p2);     delete p1;   }   //Const base initialized with derived, cannot be down- and const-casted to non-const derived   {     const Base * const p1 = new Derived;     //Removing const: will and should not compile     //Derived * const p2 = dynamic_cast<Derived*>(p1));     assert(p1);     delete p1;   }   //Base initialized with derived, can be downcasted to const derived with adding constness   {     const Base * const p1 = new Derived;     //Adding const: will and should compile     const Derived * const p2 = dynamic_cast<const Derived*>(p1);     assert(p1);     assert(p2);     assert(p1 == p2);     delete p1;     //delete p2; //Do not re-delete!   } }