Lesson 2: Functions
Activity 3: Calculating if a Person is Eligible to Vote or Not
- Include the header file in the program to print the output as shown here:
#include <iostream>
- Now, create a function named byreference_age_in_5_years and the if loop with the following condition to print the message:
void byreference_age_in_5_years(int& age) {
if (age >= 18) {
std::cout << “Congratulations! You are eligible to vote for your nation.” << std::endl;
return;
- Add the else block to provide another condition if the age of the user is less than 18 years:
} else{
int reqAge = 18;
int yearsToGo = reqAge-age;
std::cout << “No worries, just “<< yearsToGo << “ more years to go.” << std::endl;
}
}
- In the main function, create a variable of type integer and pass it as a reference in the byreference_age_in_5_years function as shown:
int main() {
int age;
std::cout << “Please enter your age:”;
std::cin >> age;
byreference_age_in_5_years(age);
}
Activity 4: Apply the Understanding of Passing by Reference or Value in Functions
- After adding all the required header files, create the first function of type integer as shown here:
int sum(int a, int b)
{
return a + b
}
Take by value, return by value, since the types are small in memory and there is no reason to use references.
- The second function should be written as follows:
int& getMaxOf(std::array<int, 10>& array1, std::array<int, 10>& array2, int index) {
if (array1[index] >= array2[index]) {
return array1[index];
} else {
return array2[index];
}
}
Activity 5: Organizing Functions in Namespaces
- Include the required header file and namespace to print the required output:
#include <iostream>
using namespace std;
- Now, create a namespace named LamborghiniCar with the following output function:
namespace LamborghiniCar
{
int output(){
std::cout << “Congratulations! You deserve the Lamborghini.” << std::endl;
return NULL;
}
}
- Create another namespace named PorscheCar and add an output function as shown:
namespace PorscheCar
{
int output(){
std::cout << “Congratulations! You deserve the Porsche.” << std::endl;
return NULL;
}
}
In the main function, create a variable named magicNumber of type integer to accept the input from the user:
int main()
{
int magicNumber;
std::cout << “Select a magic number (1 or 2) to win your dream car: “;
std::cin >> magicNumber;
- Add the following conditional if…else-if…else statement to complete the program:
if (magicNumber == 1){
std::cout << LamborghiniCar::output() << std::endl;
} else if(magicNumber == 2){
std::cout << PorscheCar::output() << std::endl;
}else{
std::cout << “Please type the correct magic number.” << std::endl;
}
}
Activity 6: Writing a Math Library for use in a 3D Game
- Add the required header files at the start of the program (mathlib.h file is provided):
#include <mathlib.h>
#include <array>
#include <iostream>
- Create a global const variable of type float as shown here:
const float ENEMY_VIEW_RADIUS_METERS = 5;
- In the main function, create two arrays of type float and assign the following values:
int main() {
std::array<float, 3> enemy1_location = {2, 2 ,0};
std::array<float, 3> enemy2_location = {2, 4 ,0};
- Now, create a variable named enemy_distance of type float and use the distance function to assign the value after calculating it:
float enemy_distance = johnny::mathlib::distance(enemy1_location, enemy2_location);
float distance_from_center = johnny::mathlib::distance(enemy1_location);
- Using the circumference function of mathlib.h, calculate and assign the enemy visual radius to view_circumference_for_enemy of type float:
using johnny::mathlib::circumference;
float view_circumference_for_enemy = circumference(ENEMY_VIEW_RADIUS_METERS);
- Create a variable named total_distance of type float and assign the distance difference between the two enemies as shown in the following code:
float total_distance = johnny::mathlib::total_walking_distance({
enemy1_location,
{2, 3, 0}, // y += 1
{2, 3, 3}, // z += 3
{5, 3, 3}, // x += 3
{8, 3, 3}, // x += 3
{8, 3, 2}, // z -= 1
{2, 3, 2}, // x -= 6
{2, 3, 1}, // z -= 1
{2, 3, 0}, // z -= 1
enemy2_location
});
- Print the output using the following print statement:
std::cout << “The two enemies are “ << enemy_distance << “m apart and can see for a circumference of “
<< view_circumference_for_enemy << “m. To go to from one to the other they need to walk “
<< total_distance << “m.”;
}
