When Constructors and Destructors Are Called

• Constructors and destructors; Called implicitly by compiler
• Order of function calls
  • Depends on order of execution; When execution enters and exits scope of objects
  • Generally, destructor calls reverse order of constructor calls
• Order of constructor, destructor function calls
  • Global scope objects
    • Constructors; Before any other function (including main)
    • Destructors
      • When main terminates (or exit function called)
      • Not called if program terminates with abort
  • Automatic local objects
    • Constructors
      • When objects defined; Each time execution enters scope
    • Destructors
      • When objects leave scope; Execution exits block in which object defined
      • Not called if program ends with exit or abort
  • static local objects
    • Constructors
      • Exactly once
      • When execution reaches point where object defined
    • Destructors
      • When main terminates or exit function called
      • Not called if program ends with abort

The program of Figs. 1.22-1.25 demonstrates the order in which constructors and destructors are called for objects of class CreateAndDestroy of various storage classes in several scopes.

Figure 1.22: CreateAndDestroy class definition.

Figure 1.23: CreateAndDestroy class member-function definitions.

Figure 1.24: Order in which constructors and destructors are called. (part 1 of 2)

Figure 1.25: Order in which constructors and destructors are called. (part 2 of 2)