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CPP-01 Modern C++:Variables, Basic types, Control structure (2018,Igor)

Notes during the course (slides)

  • naming variables
    • name varianbles with meaning
    • do not be afrad of using long names
      • bool this_is_fun = false;
      • char current_return = '\n';
      • auto number = 10;
    • operation on arithmetic types
      • a +=1 equals to a = a +1 ; same for -=, *=, /=, etc
    • Avoid == for floating point types
    • do not use the de- increment operations within another expression, i,e. a = (a++) + ++b
    • % is modulo divisor i.e. 7 / 3 == 1
    • string with #incldue to use the std::string
    • concatenate strings with +
    • check if std is empty with stt.empty()
    • works out of the box with I/O streams
  • std::array
    • use the std::array for fixed size collections of items
    • #incldue to use the std:::array
    • store a collection of items of same type.
    • remove all elements: arr.clear()
    • number of stored items: arr.size()
    • useful access to alis: arr.front() arr.back()
  • std:vector
    • #include
    • add a new item in one of the two ways
      • vec.emplace_back(value) (prefered in C++11)
      • vec.push_back(value) [historically better known]
    • use it! it is fast and flexible
    • optimize vector resizing
      • many push_back operation force vector to change its size many times
      • reserve(n) ensures that the vector has enough memory to store n
      • this is an very important optimization
    • solve the error from the button after compile
  • variable live in scopes
    • there is a single global scope
    • all variables belongs to the scope where they have been declared
    • all variables die in the end of their scope
    • any variable can be constant
      • use the const to declare a const
      • use the const to make the variable as constant, in google style, name constants starting with a smaller letter k
  • reference to variables
    • we can add a reference to any variables
    • use the & to state that a variable is a reference
      • float& ref = original_variable
      • std::string& hello_ref = hello;
      • in fact, both the origianl vairable and the ref one are exactly the same
      • if one wants to copy large data, the reference can be a good option which is pretty cheap
      • const with reference
        • int num = 42; int& ref = num; const int& kRef = num;
  • switch statement
    • used to conditionally execute code
    • can have many case statement
    • break exits the switch block
  • while loop
    • usually used when the exact number of iterations is unknown before-wise
    • easy to form an endless loop by mistake
  • for loop
    • in C++ the for loop is very fast, use them!
    • less flexible than while but less error-prone
    • use for when the number of iterations is fixed and while otherwise
  • loop range
    • for(float num:vec); for(const auto& num:vec);
  • exit loops and iterations
    • use the break to exit the loop
    • use the continue to skip to the next iteration

Reference

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

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