Solutions for C++ Problem Set 3

12.cpp

/* Problem Set 3 Question 12 solution by Dillon Morse
 * --------------------------------------------------
 * A bank charges $10 per month plus the following check fees for a commercial
 * checking account:
 *
 * $0.10 each for fewer than 20 checks
 * $0.08 each for 20-39 checks
 * $0.06 each for 40-59 checks
 * $0.04 each for 60 or more checks
 *
 * The bank also charges an extra $15 if the balance of the account falls below
 * $400 (before any check fees are applied). Write a program that asks for the
 * beginning balance and the number of checks written. Compute and display the
 * bank's service fees for the month.
 *
 * Input Validation: Do not accept a negative value of the number of checks
 * written. If a negative value is given for the beginning balance, display an
 * urgent message indicating the account is overdrawn.
 */

#include<iostream>
using namespace std;

double get_balance() {
  double balance;

  cout << "What is your account's balance?" << '\n';
  cin >> balance;

  return balance;
}

int get_checks_written() {
  int checks_written;

  cout << "How many checks did you write?" << '\n';
  cin >> checks_written;

  return checks_written;
}

double compute_charges(double balance, int checks_written) {
  // fees is initialized as 0 so I can add to it later on.
  double fees = 0;

  if(balance < 400) {
    fees = fees + 15;
  }

  if(checks_written < 20) {
    fees = fees + 0.1 * checks_written;
  } else if(checks_written < 40) {
    fees = fees + 0.08 * checks_written;
  } else if(checks_written < 60) {
    fees = fees + 0.06 * checks_written;
  } else {
    fees = fees + 0.04 * checks_written;
  }

  return fees;
}

int main() {
  double balance = get_balance();
  int checks_written = get_checks_written();
  double charges;

  // Input validation
  if(checks_written < 0) {
    cout << "Cannot accept a negative number of checks written. " <<
            "The transaction will not complete." << '\n';
  } else {
    // Input validation
    if(balance < 0) {
      cout << "Warning: your account is overdrawn." << '\n';
    }
    
    charges = compute_charges(balance, checks_written);

    cout << "Service fees: $" << charges << '\n';
  }

  // Necessary to prevent warnings from some compilers.
  // I'm not keeping the program running in a paused state because I am running
  // it from a CLI, so letting it close is most convenient.
  return 0;
}

21.cpp

/* Problem Set 3 Question 21 Solution by Dillon Morse
 * --------------------------------------------------
 * Write a program that displays the following menu:
 *
 *   Geometry Calculator
 *   
 *     1. Calculate the Area of a Circle
 *     2. Calculate the Area of a Rectangle
 *     3. Calculate the Area of a Triangle
 *     4. Quit
 *
 *     Enter your choice (1-4):
 *
 * If the user enters 1, the program should ask for the radius of the circle
 * and then display its area.
 *
 * If the user enters 2, the program should ask for the length and width of
 * the rectangle and then display the rectangle's area.
 *
 * If the user enters 3, the program should ask for the length of the
 * triangle's base and its height, and then display its area.
 *
 * If the user enters 4, the program should end.
 *
 * Input validation: Display an error message if the user enters a number
 * outside the range of 1 through 4 when selecting an item from the menu. Do
 * not accept negative values for the circle's radius, the rectangle's length
 * or width, or the triangle's base or height.
 *
 * Make use of switch statements for selecting the operation in your solution.
 */

#include<iostream>
#include<cmath>
using namespace std;

// Define the constant pi. Beware that this only works in C++ 11.
constexpr double pi() { return std::atan(1)*4; }

int get_choice() {
  int choice;

  cout << "Geometry Calculator" << '\n'
       << '\n'
       << "1. Calculate the Area of a Circle" << '\n'
       << "2. Calculate the Area of a Rectange" << '\n'
       << "3. Calculate the Area of a Triangle" << '\n'
       << "4. Quit" << '\n'
       << '\n'
       << "Enter your choice (1-4):" << '\n';

  cin >> choice;

  return choice;
}

double circle() {
  double radius;
  double area;

  cout << "What is the radius of your circle?" << '\n';
  cin >> radius;

  area = pow(radius, 2) * pi();

  if(radius < 0) {
    // Performed for error handling
    return -1;
  } else {
    return area;
  }
}

double rectangle() {
  double length;
  double width;
  double area;

  cout << "Enter the length and width of your rectangle, seperated by a "
       << "carriage return." << '\n';
  cin >> length >> width;

  area = length * width;

  if((length < 0) || (width < 0)) {
    // Performed for error handling
    return -1;
  } else {  
    return area;
  }
}

double triangle() {
  double base;
  double height;
  double area;

  cout << "Enter the length of the base and the height of your triangle, "
       << "seperated by a carriage return." << '\n';

  cin >> base >> height;

  area = 0.5 * base * height;

  if((base < 0) || (height < 0)) {
    // Performed for error handling
    return -1;
  } else {
    return area;
  }
}

int check_errors(double input, double area) {
  if((input < 1) || (input > 4))  {
    cout << "Error: you entered an invalid choice";
    return -1;
  }
  else if(area < 0) {
    cout << "Error: you entered a negative number";
    return -1;
  }
  else return 0;
}

int main() {
  int input = get_choice();
  double area;

  switch(input) {
    case 1:
      area = circle();
      break;
    case 2:
      area = rectangle();
      break;
    case 3:
      area = triangle();
      break;
    case 4:
      // Exits the program
      return 0;
    default:
      // Breaks from the loop if there are errors
      break;
  }

  // Exits the program if there are errors
  if(check_errors(input, area) == -1) return 0;
  else {
    cout << "The area of your figure is " << area << " units squared." << '\n';

    // Necessary to prevent warnings from some compilers.
    // I'm not keeping the program running in a paused state because I am
    // running it from a CLI, so letting it close is most convenient.
    return 0;
  }
}

7.cpp

/* Problem Set 3 Question 7 solution by Dillon Morse
 * -------------------------------------------------
 * Write a program that asks the user to enter a number of seconds.
 *
 * - If the number of seconds entered by the user is greater than or equal to
 *   60, the program should display the number of minutes in that many seconds.
 * - If the number of seconds entered by the user is greater than or equal to
 *   3,600, the program should display the number of hours in that many
 *   seconds.
 * - If the number of seconds entered by the user is greater than or equal to
 *   86,400, the program should display the number of days in that many
 *   seconds.
 */

#include<iostream>
using namespace std;

string get_output(int seconds) {
  double number;
  string unit;
  string out;

  if(seconds >= 86400) {
    number = seconds / 86400.0;
    unit = "days";
  } else if(seconds >= 3600) {
    number = seconds / 3600.0;
    unit = "hours";
  } else if(seconds >= 60) {
    number = seconds / 60.0;
    unit = "minutes";
  } else {
    number = seconds;
    unit = "seconds";
  }

  // to_string is a feature introduced in C++ 11 that converts a number type to
  // a string type.
  out = to_string(number) + " " + unit;

  return out;
}

int main() {
  int seconds;
  string out;

  cout << "Enter a number of seconds" << '\n';
  cin >> seconds;

  out = get_output(seconds);

  cout << out << '\n';

  // Necessary to prevent warnings from some compilers.
  // I'm not keeping the program running in a paused state because I am running
  // it from a CLI, so letting it close is most convenient.
  return 0;
}

that is a very high level code to solve a small problem like that, lol