Intro to C++ Homework Problem Set 4 Solutions

10.cpp

/* Problem Set 4 Question 10 solution by Dillon Morse
 * --------------------------------------------------
 * Write a proram that uses nested loops to collect data and calculate the
 * average rainfall over a period of years. The program should first ask for
 * the number of years. The outer loop will iterate once for each year. The
 * inner loops will iterate twelve times, once for each month. Each iteration
 * of the inner loop will ask the user for the inches of rainfall for that
 * month.
 *
 * After all iterations, the program should display the number of months, the
 * total inches of rainfall, and the average rainfall per month for the entire
 * period.
 *
 * Input Validation: Do not accept a number less than 1 for the number of
 * years. Do not accept negative numbers for the monthly rainfall.
 */

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

int get_years() {
  int years;

  cout << "How many years did you take data for?" << '\n';
  cin >> years;

  return years;
}

vector<double> get_data(int years) {
  // vector types make it easy to perform CRUD operations on data
  vector<double> rainfall;
  int i;
  int i2;
  double input;

  for(i = 1; i <= years; i = i + 1) {
    for(i2 = 1; i2 <= 12; i2 = i2 + 1) {
      cout << "Enter your rainfall for the " << i2 << "th month of the " << i
           << "th year." << '\n';
      cin >> input;
      // Adds the user's input to as the next item in the vector
      rainfall.push_back(input);
    }
  }

  return rainfall;
}

int number_of_months(vector<double> rainfall) {
  int months = rainfall.size();

  return months;
}

double total_inches(vector<double> rainfall) {
  double sum;

  // Finds the sum of the variables in the vector by using an iterator
  for(vector<double>::iterator i = rainfall.begin(); i != rainfall.end(); ++i) {
    sum = sum + *i;
  }

  return sum;
}

double get_average(vector<double> rainfall, double inches) {
  double average = inches / rainfall.size();

  return average;
}

bool validate_input(int years, vector<double> rainfall) {
  // Return false if the input fails to validate
  if(years < 1) {
    cout << "Error: You did not enter at least one year." << '\n';
    return false;
  }
  else {
    for(vector<double>::iterator i = rainfall.begin(); i != rainfall.end(); ++i) {
      if(*i < 0) {
        cout << "Error: You entered a negative number for rainfall." << '\n';
        return false;
      }
    }
  }

  return true;
}

int main() {
  int years = get_years();
  // vector types make it easy to perform CRUD operations on data
  vector<double> rainfall = get_data(years);
  int months = number_of_months(rainfall);
  double inches = total_inches(rainfall);
  double average = get_average(rainfall, inches);

  // Quit if input validation fails
  if(!validate_input(years, rainfall)) return 0;

  cout << "Number of months: " << months << " months" <<'\n'
       << "Number of inches: " << inches << " inches" << '\n'
       << "Average rainfall: " << average << " inches" << '\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;
}

20.cpp

/* Problem Set 4 Question 10 solution by Dillon Morse
 * --------------------------------------------------
 * Write a program that generates a random number and asks the user to guess
 * what the number is. If the user's guess is higher than the random number,
 * the program should display "Too high, try again." If the user's guess is
 * lower than the random number, the program should display "Too low, try
 * again." The program should use a loop that repeats until the user correctly
 * guesses the random number.
 */

#include<iostream>
#include<ctime>
#include<cstdlib>

using namespace std;

int main() {
  int guessed_num;
  int rand_num;
  bool escape = true; // Declared with a value so it can be used with a loop
  // immediately.

  srand(time(0));
  rand_num = rand() % 10 + 1;

  cout << "I just came up with a number from 1 to 10. ";

  while(escape) {
  cout << "What do you think it is?" << '\n';
  cin >> guessed_num;

    if(guessed_num < rand_num) cout << "Too low, try again." << '\n';
    else if(guessed_num > rand_num) cout << "Too high, try again." << '\n';
    else {
      cout << "Good guess!" << '\n';
      escape = false;
    }
  }

  return 0;

  // The process is never paused by the kernel because I am running it using a
  // CLI, so allowing it to terminate after execution is most convenient.
}

4.cpp

/* Problem Set 4 Question 4 Solution by Dillon Morse
 * -------------------------------------------------
 * Running on a particular treadmill you burn 3.9 calories per minute. Write a
 * program that uses a loop to display the number of calories burned after 10,
 * 15, 20, 25, and 30 minutes.
 */

#include<iostream>
using namespace std;

const double calories_per_minute = 3.9;

int main() {
  int i;
  for(i = 10; i <= 30; i = i + 5) {
    cout << "After " << i << " minutes, " << i * calories_per_minute
         << " calories are consumed." << '\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;
}