README.md

CPP-02 Modern C++:Compilation, Debugging, Functions, Headers/Source, Libraries, Cmake (2018,Igor

Notes during the course (slides)

• compilation flags and debugging
  • Enable all warnings, treat them as errors:
    • -Wall, -Wextra, -Werror
  • Warning may not be a syntax error, but can be a potential error. therefore, fix the warnings as well
  • debugging tools gdb
    • the best option is to use the gdb
    • insanely popular and powerful
    • install the gdb GUI to debug the code as you want
• functions in C++
  • code can be organized into functions
  • functions create a scope
  • single return type from a function
  • any number of input variables of any types
  • do one thing, name show what the function does
  • write small function and have a good name
  • do not return an reference of a local variable int& sum(int a, int b);
  • simple example

  #include <vector>
  using namespace std; //
  vector<int> CreateVectorOfFullSquares(int size){
      vector<int> result(size); // vector of size 'size'
      for(int i = 0; i < size; i++){ result[i] = i * i;}
      return result;
  }
  int main(){
      auto squares = CreateVectorOfFullSquares(10);
      return 0;
  }
  

  • declare your function before you use them

  • function definition holds the implementation of the function that can even be hidden from the users

  • passing big objects

    • by default in C++, objects are copied when pass into functions
    • pass by reference to avoid copy

    void DoSmth(std::string huge_string);
    void DoSmth(std::string& huge_string);
    

  • use const reference: void DoSmth(const std::string huge_string)

    • non-const refs are mostly used in older code written before C++11

  • function overload

    • compilers infers a function from arguments
    • cannot overload based on return type
    • return types plays no roles at all

    #include <iostream>
    #incldue <string>
    using namespace std;
    string Func(int num){ return "int";}
    string Func(const string& str){ return "string";}
    int main {
        cout << Func(1) <<endl;
        cout << Func("Hello") <<endl;
        return 0;
    }
    

  • default arguements

    • only use them when readability is much better

  • do not reinvent the wheel

    • when using the std::vector, std::array, etc. try to avoid writing your own functions
    • use the #include

    std::vector<float> v;
    std::sort(v.begin(), v.end); // sort by ascending
    float sum = std::accumulate(v.begin(), v.end(),0.0f);
    float products = std::accumulate(v.begin(), v.end(),1.0f, std::multiplies<float>());
    

  • header/source seperation

    • move all declareds to header files (*.h)
    • implementation goes to *.cpp or *.cc

  • how to build this?

    • the detail of this part can be found in the given link

Reference

1. (slides)
2. Google Code Styleguide
3. C++ tutorials

Contact

• Author: Weisong Wen, PhD Candidate in Hong Kong Polytechnic University.
• Email: weisongwen@weisongwen
• Affiliation: Intelligent Positioning and Navigation Laboratory