3464 CGS - Programming using C++
Spring 2005 Exam 1
Instructions 1. Do not begin writing until you are told to do so. 2. Read all the instructions here carefully. Failure to do so will result in loss of points. 3. You have 50 mins to answer the questions. 4. Answer all questions. 5. There are 5 sheets in this exam (including this one). 6. There are three questions in this test. 7. This test is closed book, closed notes. 8. You have to write your answers on this test. You can write on both sides of the sheets. 9. Read and sign the academic honesty statement.
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1. (5 points) Answer all of the following questions. (a) (0.5 points) What is the value of f after the second statement? double f, c = 20.0; f = (9/5)*c + 32; (b) (1.5 points) What is the output of the following code snippet? (If you feel that the code will result in a compile-time or run-time error, state why). int i=0,j=5; if (j || (j/i > 5)) cout << 2*j << " "; (c) (3 points) State three main concepts in object oriented programming. Answers: (a) The value of f is 52.0. (b) The output is: 10 Hint: Short-circuit evaluation. (c) Three main concepts in object oriented programming: Data encapsulation, Information hiding and data abstraction.
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2. (10 points) Write a program which denes a structure Statistics which contains three members, one each for sum, mean and the maximum value (all doubles). You should also write three functions: Statistics CollectStats(vector<double> vec); void DisplayStats(Statistics stat); int main() CollectStats() takes a vector of doubles and returns the statistics for the vector. DisplayStats() displays the statistics. For example: Sum = 55.0 Mean = 5.5 Max = 10.55 main() declares a vector and gets the elements from the user (the user inputs 0 (zero) to mark end of input). It then computes the statistics and displays the results. Solution: #include<iostream> #include<vector> using namespace std; struct { double double double }; Statistics sum; mean; max;
Statistics CollectStats(vector<double> { vec) Statistics stats = {0,0,0); stats.max = vec[0]; for (int i=0;i < vec.size(); i++) { stats.sum += vec[i]; if (vec[i] > stats.max) stats.max = vec[i]; } stats.mean = stats.sum/vec.size(); return stats; } void DisplayStats(Statistics stat) { cout << "Sum = " << stat.sum << endl << "Mean = " << stat.mean << endl << "Max = " << stat.max << endl; } int main() 3
{ vector<double> arr; double input = 0; do { cout << "Enter a number (0 to stop):"; cin >> input; if (0 != input) arr.push_back(input); } while (0 != input); Statistics myStats = CollectStats(arr); DisplayStats(myStats); return 0; }
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3. (10 points) You are given the following class (along with its implementation): class Rupees { public: Rupees(); //Initializes rupees = 0 and paise = 0 Rupees(int r, int p); //Initialises rupees to r and paise to p double GetMoney(); // returns paise/100.0 + rupees int GetR(); //returns rupees int GetP(); // returns paise private: int rupees; (0 <= rupees) int paise; // (0 <= paise < 100) };
Now write the denition and implementation of the class Dollars which has two private integer members (dollarPart and centsPart). Neither dollar nor cents can be negative and cents should be less than 100. For this class, write the following: (1 point) a constructor that takes two integers d and c as parameters and sets dollarPart = d and centsPart = c. (1 point) a constructor that takes in a Rupees object and a positive non-zero double conversionRate. dollars = rupees * conversionRate (4 points) member operator + that adds a dollar object to the current object and returns the new object. (4 points) Overload the << operator so that if d.dollarPart = 45 and d.centsPart = 75, cout << "You have " << d << "."; will display You have $45.75 . (Note that this operator is not a member of the class). You should not call the accessor functions in class Rupees from the class Dollars. You are allowed to add one line to the denition of class Rupees (Hint: Trust in your friends).
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Additional Sheet
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