C++: Construction and initialization order guarantees

by

In all classes construction order is guaranteed: base classes, as specified from left to right followed by member variables in the order declared in the class definition. A class’s constructor body is executed once all of its bases’ and members’ constructions have completed.

In your example X is derived from Z and contains Y so the Z base object is constructed first, then the Y member y, then the construction of the X completes with the execution of X‘s constructor body.

The temporary W is needed to pass to the constructor of X, so it is constructed before the construction of the x begins and will be destroyed once the initialization of x completes.

So the program must print:

W
Z
Y
X

More Related Contents:

  1. Different behavior of C++ with default value for public vs private scope
  2. Inheriting constructors
  3. What is difference between instantiating an object using new vs. without
  4. no default constructor exists for class
  5. Order of calling constructors/destructors in inheritance
  6. Dual emission of constructor symbols
  7. Why do we not have a virtual constructor in C++?
  8. What does a colon following a C++ constructor name do? [duplicate]
  9. Can the template parameters of a constructor be explicitly specified?
  10. What is constructor inheritance?
  11. How to use base class’s constructors and assignment operator in C++?
  12. Why shared_from_this can’t be used in constructor from technical standpoint?
  13. What is a copy constructor in C++?
  14. The copy constructor and assignment operator
  15. C++: When (and how) are C++ Global Static Constructors Called?
  16. How to pass a function pointer that points to constructor?
  17. How do you use the non-default constructor for a member?
  18. Select class constructor using enable_if
  19. constructor invocation mechanism
  20. Calling a virtual function from the constructor
  21. Why is the std::initializer_list constructor preferred when using a braced initializer list?
  22. Order of constructor call in virtual inheritance
  23. Has the new C++11 member initialization feature at declaration made initialization lists obsolete?
  24. Why must const members be initialized in the constructor initializer rather than in its body?
  25. Default vs. Implicit constructor in C++
  26. Why is a default constructor required when storing in a map?
  27. Why aren’t copy constructors “chained” like default constructors and destructors?
  28. Diamond Inheritance Lowest Base Class Constructor
  29. C++ copy-construct construct-and-assign question
  30. What is the order of evaluation in a member initializer list?

Leave a Comment