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Activecode Exercises

Answer the following Activecode questions to assess what you have learned in this chapter.

Suppose you have the following code. Construct a block of code that would make the print function into a member function.

#include <iostream> #include <string> using namespace std; // Edit this code struct Student { int id, year; string name; }; void printStudent (const Student& stu) { cout << stu.id << ":" << stu.year << ":" << stu.name << endl; } int main () { Student s1 = { 56673, 2023, "Bob" }; printStudent (s1); }

Below is one way to construct the code block

#include <iostream> #include <string> using namespace std; struct Student { int id, year; string name; void print (); }; void Student::print () { Student stu = *this; cout << stu.id << ":" << stu.year << ":" << stu.name << endl; } int main () { Student s1 = { 56673, 2023, "Bob" }; s1.print(); }

Let’s make an album! Write the struct definition for Album, which should have instance variables name and year. Include a member function called check that returns true if the song was released after 2015.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to define the Album struct.

#include <iostream> using namespace std; struct Album { string name; int year; bool check (); }; bool Album::check () { if (year > 2015) { return true; } else { return false; } }

Write the necessary of code to establish the convertToSeconds member function as a part of the Time struct.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to write the convertToSeconds member function.

#include <iostream> using namespace std; struct Time { int hour; int minutes; int second; }; double Time::convertToSeconds () const { int minutes = time.hour * 60 + time.minutes; double seconds = minutes * 60 + time.second; return seconds; }

Create the Student::is_older() function as it would be defined INSIDE of the Student structure definition. This function checks if the current Student is older than another Student. The function is invoked on the current Student.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to create the Student::is_older() function.

#include <iostream> using namespace std; bool is_older(const Student& stu) const { if (age > stu.age) {return true;} else {return false;} }

Write the necessary code to initialise a constructor for type Days that takes in the number of days and initialises the member variables days, weeks, years.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to initialize the constructor.

#include <iostream> using namespace std; Days::Days (int num_days) { years = num_days / 365; Days day; num_days -= years * 365; weeks = num_days / 7; num_days -= weeks * 60.0; days = num_days; }

Let’s write two constructors for Student. One with no arguments and one with arguments.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to write the two constructors.

#include <iostream> using namespace std; Student::Student () { void Student::Student () { id = 123456789; year = 2020; name = "Alice"; } Student::Student (int id_in, int year_in, string name_in) { Student::Student construct(int id_in, int year_in, string name_in) { id = id_in; year = year_in; name = name_in; }

Implement two constructors for the Penguin structure. One should be a default constructor, the other should take arguments. The weight needs to be converted from pounds to kilograms in the second constructor

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to implement the two constructors.

#include <iostream> using namespace std; struct Penguin { int age; int weight; Penguin (); Penguin (int age_in, int weight_in); }; Penguin::Penguin () { age = 1; weight = 24; } Penguin::Penguin (int age_in, int weight_in) { age = age_in; weight = weight_in; }

Days AddDays (const Days& d1, const Days& d2) {
    int days = convertToDays (d1) + convertToDays(d2);
    return makeDays (days);
}

Write the necessary blocks of code to make the AddDays function below a member function.

#include <iostream> using namespace std; // EDIT THE CODE BELOW Days AddDays (const Days& d1, const Days& d2) { int days = convertToDays (d1) + convertToDays(d2); return makeDays (days); }

Below is one way to make the AddDays function a member function.

#include <iostream> using namespace std; Days Days::add (const Days& d2) const { int days = convertToDays () + d2.convertToDays (); Days day (days); return day; }

Write the necessary blocks of code to create a struct Penguin that stores name and age. In addition have 2 constructors and declare Penguins in main such that both are called.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to creat the Penguin struct and the 2 constructors.

#include <iostream> using namespace std; struct Penguin { int age; string name; Penguin (); Penguin (int age_in, string name); }; Penguin::Penguin () { age = 1; name = "Alice"; } Penguin::Penguin (int age_in, string name_in) { age = age_in; name = name_in; } int main () { Penguin p1 (); Penguin p2 (3, "Bob"); }

Write the necessary blocks of code in order to write a header (.h) file for the struct Student.

#include <iostream> using namespace std; // YOUR CODE HERE

Below is one way to write the header file for the Student struct.

#include <iostream> using namespace std; struct Student { // instance variables int id, year; string name; // constructors Student (int id, int year, string name); Student (); // functions void print () const; bool after (const Student& stu) const; };

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