Name ___________________

CPTR246 Spring '07 (100 total points) Exam 2

1. Pointer parameters (the old C way) In the following program that computes the taxes and total cost for a hotel stay, make all of the changes necessary to convert the call-by-reference parameters in the function “computeHotelStay” to be call by reference using pointer parameters (known as the old C way). (10 points)

#include <iostream>

const double stateTax = .06;

const double countyTax = .015;

using namespace std;

void computeHotelStay(double roomRate, int nights,

double & state, double & county, double & total)

{

double costBeforeTaxes = roomRate * nights;

state = costBeforeTaxes * stateTax;

county = costBeforeTaxes * countyTax;

total = costBeforeTaxes + state + county;

}

int main() {

double roomRate, sTax, cTax, cost;

int nights;

cout << "What is the cost of the hotel room per night: ";

cin >> roomRate;

cout << "How many nights are you staying: ";

cin >> nights;

computeHotelStay(roomRate, nights, sTax, cTax, cost);

cout << "The total cost is " << cost << endl;

return 0;

}

2. Pointer Basics To the right of the following code, write what would be displayed on the screen. (24 points)

#include <iostream>

using namespace std;

int main() {

int x = 10;

int y = 20;

int * aptr;

int * bptr;

int * cptr;

int values[5] = {10, 20, 30, 40, 50};

aptr = &x;

bptr = &y;

cptr = values;

cout << *aptr << " " << *bptr << " " << *cptr << endl;

x = 30;

*bptr = 40;

cout << x << " " << y << endl;

cout << *aptr << " " << *bptr << endl;

if (*cptr == values[0])

cout << "test 1 is true" << endl;

else

cout << "test1 is false" << endl;

if (cptr[3] == x)

cout << "test 2 is true" << endl;

else

cout << "test 2 is false" << endl;

cout << (*values + values[4] + *bptr) << endl;

cout << *(values + 2) << " " << (*values + 2) << endl;

cout << aptr[0] << endl; // extra credit (2 points)

return 0;

}

3. Structures: Assume that the following code appears in your program and the array myClass has been loaded with information on 4 students. Circle the letter of the correct answer.

struct studentSchedule{

int socSecNbr; // unique student ID number

string name; // name of the student

int numberOfCourses; // how many courses they have this semester

string course[6]; // the course codes

};

studentSchedule myClass[4]; // an array of students

studentSchedule Jane = {123456789, “Jane Doe”, 4, “CPTR125”, “MATH128”,

“PHIL115”, “SOC110”, “”, “”);

(a) Which of the following statements displays Jane’s social security number? (4 points)

a. cout << socSecNbr << endl;

b. cout << Jane(socSecNbr) << endl;

c. cout << Jane.socSecNbr << endl;

d. cout << Jane[socSecNbr] << endl;

(b) Which of the following for loops displays the names of the students in the array myClass? (4 points)

a. for (int i = 0; i < 4; i++)

cout << myClass[i].name << endl;

b. for (int i = 0; i < 4; i++)

cout << myClass.name[i] << endl;

c. for (int i = 0; i < 4; i++)

cout << myClass[i].name[i] << endl;

d. for (int i = 0; i < 4; i++)

cout << name.myClass[i] << endl;

4. Input: Explain why we need to be careful when we mix extraction (>>) with getline and get when reading input from either cin or an input file. (6 points)

5. Null-terminated Character Arrays:

Consider the following definitions of null-terminated character arrays (also known as C-strings) and other C++ code.

char firstName[20];

char lastName[20];

char fullName[40];

cout << "Enter your first name: ";

cin.getline(firstName, 20);

cout << "Enter your last name: ";

cin.getline(lastName, 20);

Using the string functions described on pages 446-447 of your text, write C++ code that will perform each of the following tasks.

· Using strcmp, write code that will display “Cool name!” on the screen if the person has the same first and last name (4 points)

· Using strcpy and strcat, write code that results in the string fullName having the contents of firstName followed by the contents of lastName (with a space in between) without changing the contents of either firstName or lastName. (6 points)

6. Complete the following function that takes two parameters, a string (as a null-terminated character array) and a character. It returns the number of times the character appears in the string. For example, the function call countChar(“Hello world”, ‘l’) would return a 3. (6 points)

Hint: It will likely be easiest to code it without the use of the string functions from the text. However, if you prefer, there are additional string functions on pages 1089-1090.

int countChar(char * str, char x){

}

7. Formatting output: Write cout statements to display the following as described. (6 points)

int x = 10;

double y = 12.345678;

a. Print x right justified in a 10-digit field.

b. Print y to the nearest hundredth.

c. Print x in hexadecimal form preceded by 0x.

8. Command Line Arguments and File Processing: (30 points)

Write a complete program that does the following:

Ø The program takes an input file that contains integers. (You can assume that the file contains integers and only integers.)

Ø The user may enter the name of the file on the command line. If they do not, prompt them for the name of the file.

Ø If the user gives you a bad file name, display an error message on the screen and end the program.

Ø Count how many integers are on the file and compute their sum. Display both values on the screen.

(An additional blank page has been added for your use.)