CppNarrow_cast.md

 

 

 

 

 

(C++) Narrow_cast

 

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++11

Compiler(s):

• G++ 4.9.2

Libraries used:

• STL: GNU ISO C++ Library, version 4.9.2

 

 

 

 

 

Qt project file: ./CppNarrow_cast/CppNarrow_cast.pro

 

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TEMPLATE = app CONFIG += console CONFIG -= app_bundle CONFIG -= qt QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra -Weffc++ -Werror SOURCES += main.cpp

 

 

 

 

 

./CppNarrow_cast/main.cpp

 

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#include <cassert> #include <stdexcept> //Copied from // * Bjarne Stroustrup. The C++ Programming Language (4th edition). 2013. //   ISBN: 978-0-321-56384-2. Chapter 11.5: Explicit type conversion. page 299. template <class Target, class Source> Target narrow_cast(Source v) {   auto r = static_cast<Target>(v);   if (static_cast<Source>(r)!=v)     throw std::runtime_error("narrow_cast<>() failed");   return r; } int main() {   try   {     narrow_cast<int>(12.34);     assert(!"Incorrect conversion from double to int should be detected by narrow_cast");   }   catch (std::runtime_error& e)   {     //OK   } }