University of Dublin

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1 University of Dublin TRINITY COLLEGE Faculty of Enginering & Systems Sciences School of Engineering Junior Freshman Engineering Trinity Term 2014 Computer Engineering I (1E3) Date Location Time Dr L. Hederman Attempt THREE questions. 1 of 6

2 1. (a) The Fibonacci series starts with 0, 1, Thereafter each term is the sum of the two previous terms Write a C++ program to print out the first 20 Fibonacci numbers, separated by a space. (8 marks) (b) Write a C++ program to process exam results as follows. The input is an unknown number of rows of results, one per student, terminated by a row with student number of 999. For example Mat1 67 1E3 54 1CS3 35 2Fr1 45 1E4 23 2BA5 78 1BA2 65 MS Mat1 61 1E3 40 1CS3 42 2Fr1 45 1E4 52 2BA5 43 1BA2 50 OPT Each row or record consists of a student number, followed by exactly 8 pairs of exam code/ marks. For each student, the output should give the student number, the code for any exam failed (<40%), the average of the marks, and the resulting grade. The grade is F if any exam is failed. Otherwise the grade is as follows: D average >= 70% P1 average >= 60% but < 70% P2 average >= 50% but < 60% P3 average >= 40% but < 50% For the input above the output would be Failed: 1CS3 1E4 Average: 51.5% Grade: F Failed: Average: 47.5% Grade: P3 (25 marks) 2 of 6

3 2 (a) Explain the role of the & s in the following program. In your answer indicate what this program prints, and what it would print if the & s were removed. void f (int& x); int main () { int y = 10; f (y); cout << "y is now " << y << endl; return 0; void f (int& x) { x = x + 50; cout << "x is now " << x << endl; (7 marks) (b) The C++ program on the next page computes the real roots of a quadratic equation and tests the accuracy of those roots. (i) Rewrite main so that it behaves like the original but uses the functions of part (iii) and part (iv). (10 marks) (ii) Write a function to compute the discriminant. This function is to be used by the qroots function (part iii). (3 marks) (iii) Write a function qroots that determines whether and how many real roots there are and computes any real roots. The declaration of this function is void qroots (double a, double b, double c, int& status, double& r1, double& r2); The status value should be set by this function as follows: 0 no real roots; 1 one real root; 2 two real roots; 3 not a quadratic at all (10 marks) 3 of 6

4 (iv) Write a function to compute the value of the quadratic at a given point, which is used to test the accuracy of the computed roots. int main() { double a, b, c, discriminant, root1, root2; cout << "Enter a, b and c:"; cin >> a >> b >> c; if (a == 0) cout << "\nthat is not a quadratic.\n"; else //a is not 0 { discriminant = b*b - 4*a*c; if (discriminant < 0) cout << "\nthe equation has no real roots.\n"; else if (discriminant == 0) { root1 = -b/(2*a); cout << "\nthe equation's only root is "; cout << root1 << endl; if ((a*root1*root1 + b*root1 + c) == 0) cout << " which is accurate.\n"; else //discriminant is > 0 { root1 = (-b + sqrt(discriminant)) / (2*a); root2 = (-b - sqrt(discriminant)) / (2*a); cout << "\nthe roots are \n" << root1; if ((a*root1*root1 + b*root1 + c) == 0) cout << " which is accurate\n"; cout << " and " <<root2; if ((a*root2*root2 + b*root2 + c) == 0) cout << " which is accurate.\n"; //end of else a is not 0 (3 marks) return 0; 4 of 6

5 3. For financial applications, dates are often represented by a day number. Assume that day number 1 is the 1st January 1900, day number 2 is the 2nd Jan 1900, and so on. Assume the following functions have been declared and implemented: bool leap_year (int year); //returns true if the year is a leap year, and false otherwise. int month_length (int month, int year); //returns the number of days in the given month of the given year (a) Write a boolean function to determine whether a day/month/year combination is a valid date. The function takes three integer parameters day, month and year, and should check that the given day is within the number of days in the given month in the given year. You must use the month_length function. (6 marks) (b) Write a C++ function daynumber, whose three integer parameters represent a date as day, month and year, and returns the corresponding daynumber. (8 marks) (c) Write a void function daymthyr that takes a daynumber and three call-byreference parameters, and sets them to the day, month and year corresponsing to the daynumber. (12 marks) (d) Write a short main program which reads in a date as day, month and year, checks that the date is valid, and if so prints out the date 90 days later. You must use functions from parts (a), (b) and (c). For example Input date: days later is 30/7/2014 Input date: Error: Invalid date (7 marks) 5 of 6

6 4. (a) Write a program to read 50 positive integers and represent them as a bar chart like the one below which plots 4, 3, 2, 0, 0, 0, 7, etc. The y-axis should extend up only as far as necessary. (10 marks) 11 * 10 ****** 9 ********** * 8 ************** ** 7 * **************** *** 6 * ****************** *** 5 * ******************** * *** 4 * * ********************** * **** 3 ** * ************************ *** **** 2 *** * * ************************** *** **** 1 *** * *** **************************** ********* (b) Write a function to search an array of strings for a specified value. The function takes a search string, an array of strings, and the size of the array and returns the number of the slot that contains the search string, or returns -1 if the search string does not appear. int search (string s, string sarray[], int size); (7 marks) (c) An input file contains exactly 500 student names and their score on an exam, e.g. JBrown 42 MBlack 55 SPrunty 68 LHughes 36. Write a program, using the search function of part (b), that reads in the data and then repeatedly asks for a name, and returns the score corresponding to that name. The program terminates when the user enters the string XXX. For example: Enter a name: LHughes Grade: 36 Enter a name: MBlack Grade: 55 Enter a name: XXX Good bye. (16 marks) University of Dublin of 6

Computer Engineering 1 (1E3)

Faculty of Engineering, Mathematics and Science School of Computer Science & Statistics Engineering Trinity Term 2017 Junior Freshman Examinations Computer Engineering 1 (1E3) DD MMM YYYY Venue 14.00 16.00