Computer Science Exam 2

• Exam 2 will cover chapters 1, 2, 3, 4, 5, 6, 7, 8, 10, 14, and the linked list portion of chapter 17.
• Expect questions from lab materials, including debugging and makefiles.
• An extra presentation on makefiles is available on Blackboard.
• All material in the book and slides from meetings 1-18 is testable.

Fill-in-the-Blanks

• Child classes extend, replace, and reuse parent class behaviors.
• Dynamically allocated memory no longer referenced by a pointer results in a memory leak.
• The destructor deallocates memory used by list nodes when the class object goes out of scope.
• Encapsulation is a method of hiding information and abstraction.
• The function to overload the <= operator would be named operator <=.
• Each linked list node stores both data and the pointer/address of the next node.
• Polymorphism refers to reusing defined objects, potentially modifying them.
• To access a "data" member via a pointer to a node, use nodePtr -> data, and for objects . is used to access data.
• * is called the dereferencing operator in C++.
• Class components are called members.
• Classes inheriting from another class inherit private properties, but they are not directly accessible by the child class.
• To override a public member function, the derived class's function must have the same name, number, and types of parameters.
• Enums are special variables that let you define sets of named constants.
• A constructor/initialization list is used to ensure class member variables are initialized.
• Aggregation represents a has-a relationship.
• The preprocessor directives #ifndef, #define, and #endif prevent multiple inclusions of a header file.

Short Answer

• "Pass by reference" in C++ shares with pointers the ability to modify the original variable. However, references are automatically dereferenced and cannot be null, unlike pointers.
• A variable declared within a while loop's control statement scope is limited to the while loop.
• Overriding parent functions in derived classes can implemented using Virtual functions, which implement late binding.
• Virtual functions enables a parent class pointer to use child class functions.
• The const keyword can be used to prevent modification of the parameter being passed.
• Dynamically allocated arrays are useful when the size is known beforehand. Vectors are preferred for dynamically sized containers, despite being more expensive.

True or False

• True, enums generate integer constants that can be named.
• True, access modifiers in a class affect the accessibility of the class's members.
• False, arrays in C++ are passed by value. They are passed by reference/pointer
• False, inheritance creates an is-a relationship
• False, a derived class cannot directly intialize private data, use setters or initialization lists.
• False, an abstract class cannot be instantiated, as abstract objects do not exist.
• False, a class's destructor is called when it goes out of scope, or when delete is called.
• True, each node in a linked list points to another node or to NULL.
• False, accessing the last element in a singly-linked list takes the most time if there is no tail.
  • Singly linked lists end with node -> node -> node -> null. Doubly linked lists are null node null.
• False, you can free memory in a linked list by iterating and calling delete instead of using delete[] m_head.
• False, the -> operator is used to access members via pointers. The . operator is used for objects.
• False, the ?: operator cannot be overloaded.
• False, accessing the nth node in a linked list requires iteration, unlike arrays.
• True, vectors store all their data contiguously in memory.
• False, In the provided class, bar is constructed before sour due to the order in the initialization list.

Code Evaluation Questions

• The code outputs:
  • UMBC CHALLENGE
  • CHALLENGE CHALLENGE
  • HACKATHON HACKATHON
• Based on the enum enum foo{A=2, B=5, C=6, D, E=10}, D's integer value is 7.
• The output would be c = 456
  • if 3 then 123, if not 3 then 456