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C++ class basics and Debugging

C++ class basics and Debugging. Jungseock Joo. C++ Class Basics. Member data and functions. Like struct Control over accessibility to its members. ( ie , public, private, friend, etc). Code example #1 – class Circle. Declaration (interface)

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C++ class basics and Debugging

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  1. C++ class basics and Debugging JungseockJoo

  2. C++ Class Basics • Member data and functions. • Like struct • Control over accessibility to its members. (ie, public, private, friend, etc)

  3. Code example #1 – class Circle • Declaration (interface) • Identify its members and their forms (type, arguments, …)

  4. Code example #1 – class Circle • Definition (implementation) • Specify the actions that the member functions must carry out.

  5. Code example #1 – class Circle • Instantiation and usage

  6. Compilation dependency

  7. Constructor • Function to be called upon creation of an object. • Initializes values of the member variables. • Default implicit constructors don’t. • NOTE : Always check to initialize variables. Some compilers do it for you, but many other don’t. Then you have undetermined garbage values, painful to debug.

  8. Destructor • Function to be called upon destroying of an object. • Releases dynamic resources allocated(memory). • Default implicit destructors don’t. • If we don’t, “Memory Leak”, painful to debug.

  9. Copy Constructor • A constructor that copies from an existing instance of the same class given as an argument. • String new_string ( old_string ); • Creates a new instance, new_string, and initialize the values of member variables from old_string. • “strcpy” used to copy the contents, not the pointer. • Implicit copy constructors perform pointer-copy: (m_text = other.m_text), may cause a problem.

  10. Assignment Operator = • Assign the values of an instance (rhs) to the other (lhs) • Just like “a = 5;”, you can define a customized assignment operator for your class. • String old_string ( “aaa” ); String new_string = old_string; // handled by copy constructor • String new_string2; new_string2 = old_string; // assignment operator - Again, implicit assignment operator performs pointer-copy.

  11. Assignment Operator = • Version 1

  12. Assignment Operator = • Version 1 • What’s wrong? • Self-assignment • string1 = string1;

  13. Assignment Operator = • Version 2 • Add a protection against self-assignment

  14. Assignment Operator = • Version 2 • Add a protection against self-assignment • Not exception-safe

  15. Assignment Operator = • Version 3 • Swap-and-copy

  16. Debugging in Visual Studio • demo

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