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Data structures and algorithms lab2


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Data structures and algorithms lab2

  2. 2. OBJECTIVES Transition from C to C++  Struct vs. classes in C++  Templates 
  3. 3. WHY C++?   C + + allows the implementation of data structures with generic data types via templates. C follows the procedural programming paradigm while C++ can follow both procedural paradigm and OOP (Which are the OOP principles?)
  4. 4. TRANSITION FROM C TO C++     Any program written in C (“.c” extension) can be compiled by a C++ compiler (“.cpp” extension); not vice versa In C we don’t have classes!!! The NAMESPACE feature in C++ is absent in case of C: avoid name collisions (namespaces are similar to Java packages- you can look for differences & similarities for the next time) Standard input & output functions differ in the two languages: in C, we have scanf and printf; in C++ we have cin>> and cout<<
  5. 5. TRANSITION FROM C TO C++ ‼ Exercise: Implement a function to sort an array of 5 elements of type double. Use a swap mechanism, which has to be implemented in another function. Hint: Pay attention to passing by value/ passing by reference! Do you remember which is the difference between them?
  6. 6. STRUCTURES VS CLASSES: STRUCTURES IN C++    We can define functions inside a structure; we can access the structure’s fields by using this-><field_name> C++ structures support inheritance Everything inside a structure is public by default Example: typedef struct complex { double re; double im; void complex_initialize(double param_re, double param_im) { this->re = param_re; this->im = param_im; } struct complex complex_conjugate() { struct complex conjugate; conjugate.complex_initialize(this->re, -(this->im)); return conjugate; } }complex;
  7. 7. STRUCTURES VS. CLASSES ‼ Exercise: Add to the complex structure new functions for the addition, division and multiplication of complex numbers.
  8. 8. STRUCTURES VS. CLASSES: CLASSES  What is a class?  What is an object?  Replace the keyword struct with the keyword class in the last exercise  C++ structures behave like C++ classes, allowing functions, contructors, destructors. The main diffrence between classes and C++ structures is that everything inside a structure is public, by default, while everything inside a class is private, by default
  9. 9. STRUCTURES VS. CLASSES: CLASSES ‼ Exercise: Make a Complex class using the previous exercise. Hint: Don’t forget about the fact that everything inside a class is private, by default. Take into account the Encapsulation principle!
  10. 10. TEMPLATE CLASSES    Templates are a feature of the C++ programming language that allow functions and classes to operate with generic types. This allows a function or class to work on many different data types without being rewritten for each one. Templates are of great utility to programmers in C++, especially when combined with multiple inheritance and operator overloading. Similar to Java Generics template<typename T> class class_name { ... }  A normal class definition will be prefixed by template<typename T>  The type T can now be used as a valid type within the class  we can have variables, function arguments and function return values of type T  Everything happens at compile time, not runtime  The compiler analyzes how you use the class
  11. 11. TEMPLATE CLASSES: EXAMPLE template<typename T> class KeyStorage { public: int key; T member; //a generic member: we don't know its type when creating the class }; int main() { //Everything happens to compile time, not to run time //The compiler analyses the way in which you use the class KeyStorage<long> keyElement1; KeyStorage<int> keyElement2; return 0; } ‼ Exercise: Make a constructor, a destructor, a getter and a setter for the template class KeyStorage.
  12. 12. HOMEWORK    Finish all the lab exercises. Implement a template class for storing the coordinates of a point. Add corresponding methods for moving a point(along Ox, along Oy, along both Ox and Oy). Using the implemented class, develop an application for moving a point inside a rectangle of dimensions 1 x N, where N is given by the user. Start from the origin. Implement a template class for bank accounts with corresponding methods(deposit, withdrawal, balance display, display owner etc). Develop an application that uses this class.
  13. 13. INTERVIEW: Does overloading exist in C++?  Do abstract classes exist in C++?  When is it better to use abstract classes and when templates?  Do static classes exist in C++? 