Skip to main content

Order of Construction and Destruction in C++ with OOP: Constructors and Destructors

 

Order of Construction and Destruction in C++ with OOP: Constructors and Destructors

Constructors and destructors are crucial aspects of object-oriented programming in C++. Understanding their order of execution is important for avoiding unexpected behavior and ensuring proper resource management. Here's a breakdown:

Construction:

  • Base class to Derived class: When creating an object of a derived class, the constructors are called in the following order:
    1. Base class constructors: Each base class constructor is called in the reverse order of their declaration in the derived class hierarchy. This ensures proper initialization of base class resources.
    2. Derived class constructor: Finally, the derived class constructor is called.

Destruction:

  • Derived class to Base class: Conversely, during object destruction, destructors are called in the opposite order of constructor calls:
    1. Derived class destructor: First, the derived class destructor is called.
    2. Base class destructors: Then, each base class destructor is called in the order of their declaration. This guarantees resources acquired by the base class are released before the derived class is fully deallocated.

Key points to remember:

  • This order follows the Last-In-First-Out (LIFO) principle, similar to a stack.
  • Destructors of non-virtual base classes follow the declaration order during destruction.
  • Virtual base classes have a slightly different mechanism, but the principle of reverse construction order still applies.
  • Understanding this order is crucial for avoiding issues like dangling pointers or incomplete resource cleanup.

Additional notes:

  • Member variables within a class are constructed/destructed in the order they are declared.
  • Virtual destructors ensure proper base class destruction even in case of polymorphism.
  • Always be mindful of resource management and cleanup in your constructors and destructors.

Comments

Post a Comment

Popular posts from this blog

C++ Functions

C++ Functions A function is a block of code that performs a specific task. Suppose we need to create a program to create a circle and color it. We can create two functions to solve this problem: a function to draw the circle a function to color the circle Dividing a complex problem into smaller chunks makes our program easy to understand and reusable. There are two types of function: Standard Library Functions:  Predefined in C++ User-defined Function:  Created by users In this tutorial, we will focus mostly on user-defined functions. C++ User-defined Function C++ allows the programmer to define their own function. A user-defined function groups code to perform a specific task and that group of code is given a name (identifier). When the function is invoked from any part of the program, it all executes the codes defined in the body of the function. C++ Function Declaration The syntax to declare a function is: returnType functionName (parameter1, parameter2,...) { // func...
Post a Comment
Read more

Understanding Multidimensional Arrays:

  Understanding Multidimensional Arrays: Think of a multidimensional array as a collection of smaller arrays nested within each other, forming a grid-like structure. Each element in the grid is accessed using multiple indices, one for each dimension. Declaration and Initialization: C++ data_type array_name[dimension1][dimension2][...][dimensionN]; // Example: 3D array to store temperatures (city, month, day) int temperatures[ 3 ][ 12 ][ 31 ]; // Initialization in one line double prices[ 2 ][ 3 ] = {{ 1.99 , 2.50 , 3.75 }, { 4.20 , 5.99 , 6.45 }}; Use code  with caution. content_copy Accessing Elements: Use multiple indices within square brackets, separated by commas: C++ int first_temp = temperatures[ 0 ][ 5 ][ 10 ]; // Access temperature of city 0, month 5, day 10 prices[ 1 ][ 2 ] = 7.00 ; // Update price in row 2, column 3 Use code  with caution. content_copy Important Points: Dimensions:  The total number of elements is calculated by multiplying the dimen...
Post a Comment
Read more

C++ Variable

C++ Variables: Named Storage Units In C++, variables serve as named boxes in memory that hold values during program execution. Each variable has three key aspects: 1. Data Type: Defines the kind of data a variable can store: numbers (integers, floating-point, etc.), characters, boolean values (true/false), or custom data structures (arrays, objects). Common data types: int : Whole numbers (e.g., -10, 0, 23) float : Decimal numbers (e.g., 3.14, -2.5) double : More precise decimal numbers char : Single characters (e.g., 'a', 'Z', '&') bool : True or false values 2. Name: A user-defined label for the variable, chosen according to naming conventions: Start with a letter or underscore. Contain letters, digits, and underscores. Case-sensitive (e.g.,  age  and  Age  are different). Not a reserved keyword (e.g.,  int ,  for ). Choose meaningful names that reflect the variable's purpose. 3. Value: The actual data stored in the variable, which must match its data...
Post a Comment
Read more