Review for Test 1 (Chapter 1-5)

Transcription

1 Review for Test 1 (Chapter 1-5) 1. Software development 1. Pre-conditions and Post-conditions 2. Running time analysis Big O Timing loops and nested loops 1) Write the simplest big-o expression to describe the number of operations required for the following algorithm: for (i = 1; i < N; ++i)...statements that require exactly i operations... } 2) Which of these statements will always cause a program to halt? (x is an int variable). A. assert(10 > 0); B. assert(10 < 0); C. assert(x < 0); D. None of the above will always cause a program to halt. 3) Which of the following formulas in big-o notation best represent the expression n²+35n+6? A. O(1) B. O(log n) C. O(n) D. O(n²) 2. Data modeling 1. Classes in C++ 2. Access restrictions private and public Friends 3. Role of header files and implementation files 4. Namespace usage When defining resources in a namespace When using resources in a namespace 5. Constructors Purpose Syntax Default parameter values 6. Value semantics

2 What happens when a copy is made: deep copy & shallow copy 3. Function parameters 1. Value parameters 2. Reference parameters 4. Overloading operators 1. Syntax for member function 2. Syntax for non-member function 1) Here is part of the throttle declaration: class throttle public: void shut_off(); double flow();... private: int position; }; Write several lines of C++ code to declare a throttle called quiz, activate the member function that shuts off quiz's flow, and then print the current flow from quiz. 2) Suppose that you define a new class called foo. For two foo objects x and y, you would like the expression x+y to be a new foo object. What is the prototype of the function that you must write to enable expressions such as x+y? 3) Here is a function prototype and some possible function calls: int day_of_week(int year, int month = 1, int day = 1); // Possible function calls: cout << day_of_week( ); cout << day_of_week(1995); cout << day_of_week(1995, 10); cout << day_of_week(1995, 10, 4); How many of the function calls are illegal? 5. bag class 1. Comparing implementations What are consequences of using a regular array What are the consequences of using a dynamic array 2. Using a bag 3. Implementation of bag functions 6. STL multiset 1. Creating and filling a multiset

3 2. Using an iterator 1) Suppose that I have the following declarations: int data[100]; size_t i; Write a small segment of C++ code that will shift data[50]...data[98] up one spot to the locations data[51]...data[99]. Then insert the number 42 at location data[50]. 2) Suppose that the bag class is efficiently implemented with a fixed array with a capacity of 4000, as in Chapter 3 of the class text. Choose the best description of b's member variables after we execute these statements: bag b; b.insert(5); b.insert(4); b.insert(6); b.erase_one(5); What will be the values of b.used and b.data after the statements? A. b.used is 2, b.data[0] is 4, b.data[1] is 6 B. b.used is 2, b.data[0] is 6, b.data[1] is 4 C. b.used is 3, b.data[0] is 4, b.data[1] is 6 D. b.used is 3, b.data[0] is 6, b.data[1] is 4 7. Pointers and dynamic arrays 1. Pointers What they are Declaring Address operator Dereference 2. Dynamic allocation 3. Deallocation 4. How the dynamic array in bag is managed 5. Value semantics Copy constructor Assignment operator Destructor 1) Suppose that p is an int* variable. Write several lines of code that will make p point to an array of 100 integers, place the numbers 0 through 99 into the array components, and then deallocate the dynamic array. 2) What are the outputs of the following code:

4 int i = 42; int k = 80; int* p1; int* p2; p1 = &i; p2 = &k; cout<<*p1<< <<*p2<<endl; *p1 = *p2; cout<<*p1<< <<*p2<<endl; *p1 = 35; *p2 = 17; cout<<i; 3) When should a pointer parameter p be a reference parameter? A. When the function changes p, and you want the change to affect the actual pointer argument. B. When the function changes p, and you do NOT want the change to affect the actual pointer argument. C. When the function changes *p, and you want the change to affect the object that is pointed at. D. When the function changes *p, and you do NOT want the change to affect the object that is pointed at. E. When the pointer points to a large object. 4) Suppose you have the following function prototype and variable declaration: void goop(int z[ ]); int x[10]; Which is the correct way to call the goop function with x as the argument: A. goop(x); B. goop(x[ ]); C. goop(x[10]); D. goop(&x); E. goop(&x[ ]); 5) Here is a function declaration: void goo(int* x) *x = 1; } Suppose that a is an int* variable pointing to some integer, and *a is equal to zero. What is printed if you print *a after the function call goo(a)? A. 0 B. 1 C. address of a D. address of x E. None of the above

5 6) Here is a small function that uses the dynamic bag class from Chapter 4: void quiz( ) bag::size_type i; // Line 1 bag b; // Line 2 b.insert(42); // Line 3 i = b.size( ); // Line 4 cout << i; // Line 5 } When is the bag's dynamic array allocated? A. During the execution of Line 2. B. During the execution of Line 3. C. Just after Line 4 and before line 5. D. After Line 5. 7) What is the usual worst-case performance for resizing a container class that stores its data in a dynamic array? A. Constant time B. Logarithmic time C. Linear time D. Quadratic time 8) Suppose that you want to declare an array of characters to hold a C++ string with exactly 9 letters. Which declaration is best? A. char s[8]; B. char s[9]; C. char s[10]; D. char s[11]; E. char s[12]; 8. Link List 1. Node 2. Toolkit 1) Suppose we are using the usual node definition (with member functions called data and link). Your program is using a node* variable called head_ptr to point to the first node of a linked list (or head_ptr == NULL for the empty list). Write a few lines of C++ code that will print all the double numbers on the list. 2) Implement the following function as a new function for the linked list toolkit. (Use the usual node definition with member variables called data and link. The data field is an int.)

6 int sum(const node* head_ptr); // Precondition: head_ptr is the head pointer of a linked list. The list might be empty or it might be non-empty. // Postcondition: The return value is the sum of all the data components of all the nodes. NOTE: If the list is empty, the function returns 0. 3) Compare the worst-case big-o time analysis for these two functions: The insert function for the bag that is implemented using a fixed-sized array, and the insert function for the bag that is implemented using a linked list. 4) In the linked list version of the bag class a member variable many_nodes is used to keep track of how long the linked list is. Why not just make a call to the list toolkit function list_length()? A. The list_length() function is O(n) and the alternative is O(1). B. The list_length() function is private. C. The list_length() function results in an infinite loop for circular lists. D. The list_length() function works only for lists of integers. 5) Which expression computes a pseudorandom integer between -10 and 10 using rand() from cstdlib? A. (rand( ) % 20) - 10 B. (rand( ) % 21) - 10 C. (rand( ) % 22) - 10 D. (rand( ) % 20) - 11 E. (rand( ) % 21) 11 6) What kind of list is best to answer questions such as "What is the item at position n?" A. Lists implemented with an array. B. Doubly-linked lists. C. Singly-linked lists. D. Doubly-linked or singly-linked lists are equally best