(C++) ExerciseDivideAnswer

 

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: ./CppExerciseDivideAnswer/CppExerciseDivideAnswer.pro

 

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include(../../ConsoleApplication.pri) SOURCES += main.cpp

 

 

 

 

 

./CppExerciseDivideAnswer/main.cpp

 

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#include <cassert> #include <stdexcept> #include <memory> //Features: // - client has to check the four outputs of this function: //   - returns std::numeric_limits<double>::infinity() if numerator less than zero and denominator equals zero //   - returns NaN if numerator and denominator are zero //   - returns -std::numeric_limits<double>::infinity() if numerator above zero and denominator equals zero //   - returns correct value if denominator is unequal to zero // - noexcept double DivideNaive(const double numerator, const double denominator) noexcept {   return numerator / denominator; } //Features: // - clear interface for client to use this function // - no decrease in run-time speed during release, as denominator is not checked then // - noexcept double DivideBilderbeek(const double numerator, const double denominator) noexcept {   assert(denominator != 0.0);   return numerator / denominator; } //Features: // - clear interface for client to use this function // - decrease in run-time speed during release, as denominator is still checked then double DivideMeyers(const double numerator, const double denominator) {   assert(denominator != 0.0);   if (denominator == 0.0) throw std::logic_error("Cannot divide by 0.0");   return numerator / denominator; } //Features: // - client has to check the outputs of this function: //   - returns nullptr if denominator is equal to zero //   - returns correct value if denominator is unequal to zero // - noexcept // - client has to delete the pointer double * DivideRawPointer(const double numerator, const double denominator) noexcept {   if (denominator == 0.0) return nullptr;   return new double(numerator / denominator); } //Features: // - client has to check the outputs of this function: //   - returns empty std::unique_ptr if denominator is equal to zero //   - returns correct value if denominator is unequal to zero // - noexcept // - std::unique_ptr takes care of its own deletion std::unique_ptr<double> DivideUnique_ptr(const double numerator, const double denominator) noexcept {   if (denominator == 0.0) return nullptr;   return std::make_unique<double>(numerator / denominator); } //Features: // - client has to check the outputs of this function: //   - first is false, if denominator is equal to zero //   - if first is true, the correct value is in second // - noexcept std::pair<bool,double> DividePair(const double numerator, const double denominator) noexcept {   if (denominator == 0.0) return std::make_pair(false,0.0);   return std::make_pair(true,numerator / denominator); } //Features: // - client has to supply both arguments // - client has to check the outputs of this function: //   - sets success to false if denominator is equal to zero //   - sets success to true and result to the correct value if denominator is unequal to zero // - noexcept void DivideReference(const double numerator, const double denominator, bool& success, double& result) noexcept {   if (denominator == 0.0)   {     success = false;     result = 0.0;   }   else   {     success = true;     result = numerator / denominator;   } } #include <iostream> #include <limits> int main() {   for (int i=-1; i!=2; ++i)   {     const double result{DivideNaive(static_cast<double>(i),0.0)};     if (result != result) {std::cout << "NaN detected" << '\n';}     if (result == std::numeric_limits<double>::infinity()) {std::cout << "Infinity detected" << '\n';}     if (result == -std::numeric_limits<double>::infinity()) {std::cout << "-Infinity detected" << '\n';}   } }