True or False (15 Points)

Transcription

1 Name Number True or False (15 Points) 1. (15 pts) Circle T for true and F for false: T F a) Void Functions cannot use reference parameters. T F b) Arguments corresponding to value parameters can be variables only. T F c) The C++ statement return; can be used with a value-returning function T F d) Static variables maintain their value from function call to function call. T F e) The members of a C++ structure must be homogeneous T F f) A hierarchical structure has at least one component that is itself a structure. T F g) All members of a union can hold a valid value at the same time T F h) If a function has a reference parameter, the corresponding argument may be a variable, a constant, or an arbitrary expression. T F i) Input file stream parameters are always value parameters, and output file stream parameters are always reference parameters. T F j) With respect to a given block, an identifier is called non-local if it has been declared outside of that block T F k) The names of members in a structure do not have to be unique for that structure T F l) The expression name.first could be used to access the first member of the structure variable name. T F m) The lifetime of a local variable is for the duration of the program T F n) Local identifiers have name precedence over global identifiers with the same name. T F o) A static variable is one in which memory is allocated and deallocated when control enters and exits the block in which it is declared? Extra Credit #1 (2 pts) The code given out in class on Monday 3/27 and Tuesday 3/28 is which of the following? (name must be on list to receive credit) A) Final B) Bonus C) Test 3 D) Code E) I don t need a code Page 1 of 11

2 Multiple choice (11 points) Questions 2 12 For these problems circle all correct answers. For example if answers A, C and E are all valid then circle A, C and E. 2. How many function values does a value-returning function have? A) 4 B) 2 C) As many as necessary D) 1 E) 3 F) None of these 3. A function that does not return a function value is known as what kind of function? A) Value returning function B) Reference Parameter C) Empty D) Void function E) Expression less F) None of these 4. Circle all operations that ARE ALLOWABLE aggregate operations on structures. A) Input/Output (cin, cout statements) B) Assignment C) Arithmetic D) Return as a functions return value E) Comparison F) Argument pass by value to a function G) Argument pass by reference to a function 5. Value parameters (passing by value) are used if a parameters data flow is A) One-way, into the function B) One-way, out of the function C) Two-way, into and out of the function D) None of these 6. The void function named GetNums has two parameters A pass-by-value parameter named x of type float A pass-by-value parameter named num of type int. Which of the following choices is a valid function heading given the description of the parameters for the function GetNums? A) void GetNums( float&, int& ) B) void GetNums( float& x, int& num ) C) void GetNums( float x, int num) D) void GetNums(float, int) E) none of the above Page 2 of 11

3 7. Reference parameters (passing by reference) are used if a parameters data flow is: A) two-way, into and out of the function B) one-way, into the function C) one-way, out of the function D) None of these 8. What are the reference parameters in the following function heading? void DoSomething(string date, int num, float average, float sum, string name) A) date B) num C) average D) sum E) name F) None of them 9. What are the value parameters in the following function heading? void DoSomething(string& date, int num, float& average, float sum, string& name) A) date B) num C) average D) sum E) name F) None of them 10. The void function named GetNums has two parameters A pass-by-value parameter named x of type float A pass-by-reference parameter named num of type int. Which of the following choices are correct function prototypes for the description of the parameters for the function GetNums? A) void GetNums( float&, int& ); B) void GetNums( float& x, int& num ); C) void GetNums( float, int num ); D) void GetNums(float, int); E) none of the above 11. Given the declarations below, which of the following assignment statements are valid? struct RecType A) myrec.length = yourrec.length; int length; B) myrec = yourrec; float width; ; C) myrec.length = (int) yourrec.width; RecType myrec; RecType yourrec; D) None of the above are correct Page 3 of 11

4 12. A(n) parameter is a parameter that receives a copy of the value of the corresponding argument. A) Function B) Value C) Variable D) Reference E) None of these Short Answer (74 points) Questions (6 pts) Given the following definitions/declarations. const int SIZE = 10; int sum; float average; string name; void square(float); // function prototype Based on the above declarations, the following list of expressions are to be considered for arguments in a function call: a) average b) sum c) name d) B e) square(average) f) SIZE g) name h) Word A) List all expressions above that are valid for use as arguments paired with value parameters? B) List all expressions above that are valid for use as arguments paired with reference parameters? Page 4 of 11

5 14. (8 pts) Rewrite the void function definition below as a value returning function definition. The value returning function is to return sub as its function value and the function has prompt as its only parameter. void FindSub(string& sub, string prompt) string line; cout << prompt; getline(cin, line, \n ); sub = line.substr(line.size()/2, line.size()); 15. (6 pts) Write the type declaration for a struct DataType named Appointment containing the following members: - a string variable representing the name of the appointment - A Date variable indicating the date of the appointment where Date is a structure already defined - A Time variable indicating the time of the appointment where Time is a structure already defined Page 5 of 11

6 16. (10 pts) Consider the following structure declarations when answering the questions below. struct Date int day; int month; int year; ; struct Person string name; string city; int age; Date dob; // dob = date of birth ; a) Write a statement that declares the identifier Sam as a variable of DataType Person. b) Write a cout statement that will output the value of age of the variable Sam. c) Write a statement that declares the identifier Jane_Doe as a variable of DataType Person. d) Write a statement that assigns a value of 1950 to the year of the dob of Jane_Doe. e) Write a cout statement that will output the value of month of the dob of Jane_Doe. 17. (4 pts) What is wrong (if anything) with the following C++ function definition? Explain your answer int Function_A(float miles, float& gallons) float miles; float result; result = miles/gallons; return result; Page 6 of 11

7 18. (8 pts) For the following code segment, write out what is printed to the screen. Show the displayed output precisely by using the following rules: o Write one character per box. o Skip a box to indicate the presence of a blank space in the output. o Skip a row to indicate the presence of a blank line in the output. #include <iostream> using namespace std; void Sum(int&); int main() int add = 4; Sum(add); Sum(add); Sum(add); Sum(add); return 0; void Sum(int& add) static int sum = 0; static int j = 1; sum = sum + add; cout << j << << sum << endl; j++; add--; Page 7 of 11

8 19. (8 pts) When the program shown below is executed, what is the output to the screen? This problem deals with the scope of a variable in a program, and the order of execution of statements. #include <iostream> using namespace std; void function_a(int&); void function_b(int); int number = 4; int main() int number = 3; function_a(number); cout << number in main is: << number << endl; return 0; void function_a(int& num) int number = 5; function_b(num); cout << number in function A is: << number << endl; num = num +3; void function_b(int sum) cout << sum in function B is: << sum << endl; cout << number in function B is: << number << endl; sum = sum + 1; The identifying phrases written by the output statements in this program are shown below. In the blank to the left of the lines, place 1,2,3 or 4 to indicate the order the statements are printed (1 for first, 4 for last). The value output is placed in the blank at the end of the line. number in main is: number in function A is: number in function B is: sum in function B is: Page 8 of 11

9 20. (12 pts) Finish the program below by adding a void function as specified below. Add only a function prototype, function call statement and function definition to the following program. The name of the void function is InitStruct. The function has one parameter of the struct DataType Name. The function is to initialize each member of the structure parameter with a value of NoName. The information stored in the parameter must be available in main() after the function call. #include <iostream> using namespace std; struct Name string first; string middle; string last; ; // Place the function prototype below this line int main() Name person; // Place the function call statement below this line return 0; // Place the function definition below this line Page 9 of 11

10 21. (12 pts) Write a void function definition that is described below: The name of the void function is OpenInput. The function has one parameter an input file stream. The function is to: a) Prompt the user for the name of an input file and read it. b) Open the file. c) If the file did not open successfully, print out a message stating as such, reset the input stream variable (code to do this is infile.clear();) d) Repeat steps a,b,c until a file is successfully opened or the user enters ctrl-c. Page 10 of 11

11 Extra Credit #2 (5 pts) For this problem show precisely the displayed output o Write one character per box. o Skip a box to indicate the presence of a blank space in the output. o Skip a row to indicate the presence of a blank line in the output. The following program is executed. What is the output to the screen? #include <iostream> using namespace std; void Sum(int&, int ); int main() int num = 5, sum = -1 ; Sum(num,sum); cout << Num: << num << Sum: << sum << endl; return 0; void Sum(int& num, int sum) do sum=sum+num; cout << Sum: << sum << endl; num=num-1; while(num>=1); Page 11 of 11