Monday, October 30, 6pm - 8pm ME 3380 Thursday, November 2, 6pm - 8pm ME 4499

Transcription

1 It is most beneficial to you to write this mock midterm UNDER EXAM CONDITIONS. This means: Complete the midterm in 80 minutes. Work on your own. Keep your notes and textbook closed. Attempt every question. After the time limit, go back over your work with a different colour or on a separate piece of paper and try to do the questions you are unsure of. Record your ideas in the margins to remind yourself of what you were thinking when you take it up at PASS. The purpose of this mock exam is to give you practice answering questions in a timed setting and to help you to gauge which aspects of the course content you know well and which are in need of further development and review. Use this mock exam as a learning tool in preparing for the actual exam. Please note: Come to the PASS workshop with your mock exam complete. During the workshop you can work with other students to review your work. Often, there is not enough time to review the entire exam in the PASS workshop. Decide which questions you most want to review the Facilitator may ask students to vote on which questions they want to discuss in detail. Facilitators do not bring copies of the mock exam to the session. Please print out and complete the exam before you attend. Facilitators do not produce or distribute an answer key for mock exams. Facilitators help students to work together to compare and assess the answers they have. If you are not able to attend the PASS workshop, you can work alone or with others in the class. Good Luck writing the Mock Exam!! Dates and locations of mock exam take-up: Monday, October 30, 6pm - 8pm ME 3380 Thursday, November 2, 6pm - 8pm ME 4499

2 Question 1 void initarraya(int *a, int n){ for (int i = 0; i < n; i++) a[i] = i + 1; void initarrayb(int a[], int n){ for (int i = 0; i < n; i++) { *a = i + 1; a++; void initarrayc(int *a, int n){ for (int i = 0; i < n; i++) *(a + i) = i + 1; void initarrayd(int a[], int n){ for (int i = n; i > 0; i--) *(a + i - 1) = i; void initarraye(int a[], int n){ for (int i = 0; i < n; i++) *(&a[i]) = i + 1; int main(void){ int arr[10]; ; return 0; // Note: A single line for or while loop does not require braces // Question continues on next page

3 Substituted into the blank line, which of these function calls will correctly initialize "arr" with the values 1 to 10? Mark all that apply. a) initarraya(arr, 10); b) initarrayb(arr, 10); c) initarrayc(arr, 10); d) initarrayd(arr, 10); e) initarraye(arr, 10); f) initarraya(arr[], 10); g) initarrayb(arr[], 10); h) initarrayc(arr[], 10); i) initarrayd(arr[], 10); j) initarraye(arr[], 10); k) initarraya(&arr[0], 10); l) initarrayb(&arr[0], 10); m) initarrayc(&arr[0], 10); n) initarrayd(&arr[0], 10); o) initarraye(&arr[0], 10); p) initarraya(*arr, 10); q) initarrayb(*arr, 10); r) initarrayc(*arr, 10); s) initarrayd(*arr, 10); t) initarraye(*arr, 10); u) initarraya(&arr, 10); v) initarrayb(&arr, 10); w) initarrayc(&arr, 10); x) initarrayd(&arr, 10); y) initarraye(&arr, 10); z) initarraya(*(&arr), 10);

4 Question 2 1. typedef struct point3d { int x; int y; int z; point3d_t; 2. struct point3d { int x, y, z; ; typedef struct point3d point3d_t; 3. typedef struct { int x, y, z; point3d_t; 4. struct point3d home = {0, 0, 0; point3d_t * homeptr = &home; 5. point3d_t home; home.x = 0; home.y = (&home)->x; home.z = home.y; struct point3d* homeptr = &home; 6. struct point3d home; point3d_t *homeptr = &home; homeptr->x = 0; (*homeptr).y = 0; homeptr->z = home.y; 7. point3d_t *homeptr = malloc(sizeof(point3d_t)); point3d_t home = *homeptr = (point3d_t) {0, 0, 0; 8. point3d_t home; point3d_t *homeptr = &home; *homeptr = (struct point3d) {0, 0, 0; Which of the statements 1, 2, and 3 are equivalent? Mark all that apply. a) 1 b) 2 c) 3 Assuming the struct has been defined as on line 1: Which of 4, 5, 6, 7, and 8 are functionally equivalent? Mark all that apply. a) 4 b) 5 c) 6 d) 7 e) 8

5 Question 3 Referring to Question 2, which of the statements will allocate memory for a struct in the stack? Mark all that apply. a) 1 b) 2 c) 3 d) 4 e) 5 f) 6 g) 7 h) 8 Question 4 void changeptr(int *ptr){ ptr = ptr + 1; *ptr = *ptr + 1; int main(void){ int p = 0; int *x = &p; changeptr(x); // Breakpoint return 0; After changeptr(x) returns, what are the values of x and p? (It may help to draw a memory diagram.) a) x: x + 1 p: 1 b) x: unchanged p: 0 c) x: unchanged p: 1 d) x: x + sizeof(int) p: 1

6 Question 5 Write the following one-line functions like so: <return type> f( <input type> p){ return <some expression>; ex: Write a function f that takes an int p and returns the value of p. int f(int p){ return p; a) Write a function f that takes a pointer p to an int and returns the value of the variable pointed to by p. b) Write a function f that takes a pointer p to an int and returns the address of the variable pointed to by p. c) Write a function f that takes an int p and returns the address of p. d) Write a function f that takes a pointer p to the first element in an array of integers and returns the value of the next element. e) Write a function f that takes a pointer p to the first element in an array of integers and returns the address of the next element. f) Write a function f that takes a struct point3d p and returns the value of its member x. (See Question 2)

7 g) Write a function f that takes a struct point3d p and returns the address of its member x. (See Question 2) h) Write a function f that takes a pointer p to a point3d_t and returns the value of its member x. (See Question 2) i) Write a function that takes a pointer p to a point3d_t and returns the address of its member x. (See Question 2) j) Write a function that takes a pointer p to a point3d_t and returns the struct itself. (See Question 2) Question 6 int a = 0; int *b = &a; *b = 5; int c = &b; int d = a; What are the values of a, b, c and d? (It may help to draw a memory diagram.) a) a: 0 b: 5 c:? d: 0 b) a: 5 b:? c:? d: 5 c) a: 5 b: 5 c: 5 d: 5 d) a: 0 b: 5 c:? d: 0

8 Question 7 typedef struct { int studentid; int grades[5]; double cgpa; student_t; void calccgpa(student_t *student){ double sumgrades = 0; int numcourses = 5; int *data = student->grades; // Breakpoint 2 for(int i = 0; i < numcourses; i++){ sumgrades += *data; data++; student->cgpa = sumgrades / numcourses; // Breakpoint 3 int main(void) { // Breakpoint 1 student_t *abu = malloc(sizeof(student_t)); *abu = (student_t) { , {8, 11, 10, 9, 12, 0; calccgpa(abu); return 0; a) Draw a C-tutor style memory diagram at Breakpoint 1 (program just begun). Stack Heap

9 Question 7 continued b) Draw a C-tutor style memory diagram at Breakpoint 2 (just before the loop). Stack Heap d) Draw a C-tutor style memory diagram at Breakpoint 3 (just before calccgpa returns). Stack Heap

10 Question 8 for (int i = 0; i < 7; i += 7){ i++; How many times will this loop run? a) 0 b) 1 c) 4 d) 6 e) 7 Question 9 int f(int x){ x++; return x; int main(void){ int x = 5; int y = f(f(f(f(x)))); // Breakpoint return 0; At the breakpoint (just before main returns) what is the value of x and of y? a) x:5, y:6 b) x:6, y:6 c) x:9,y:9 d) x:5, y:9 Question 10 int * interlacearrays(int *a, int *b, int n){ ; for (int i = 0; i < n; i++){ out[2 * i] = a[i]; out[2 * i - 1] = b[i]; return out; What does it seem like this function does? What goes on the missing line to make it work? a) int out[2 * n] b) int *out = malloc(sizeof(int * n) * 2) c) int *out = malloc(sizeof(a) + sizeof(b)) d) int *out = malloc(sizeof(a[0]) * 2 * n)