Question

In C++ please! Please include .cpp and .hpp files! Thank you!

Recursive Functions

Goals

• Create and use recursive functions

In this lab, we will write a program that uses three recursive functions.

Requirements:

Important: You must use the array for this lab, no vectors allowed.

1. First Recursive Function

Write a function that recursively prints a string in reverse. The function has ONLY one parameter of type string. It prints the reversed character to the screen followed by a newline character.

Example: Input of “Hello, world” should output “dlrow ,olleH(newline)”.

Note: Your recursive function just needs to print the reverse of the string rather than actually reversing the string itself.

2. Second Recursive Function

Write a function that recursively calculates the sum of an array of integers. The function has 2 parameters:

• A pointer to the integer array
• An integer for the number of elements in the array.

The function must use a recursive call to sum the value of all integers.

3. Third Recursive Function

Write a function that recursively calculates the triangular number of an integer N. You can set an up-limit for N. You don’t need to handle extra large integers.

The function has one parameter that take in integer N.
Example: If the integer N is 3, the function should output the triangular number 6, since 1 + 2 + 3 = 6.

For more information on triangular number: https://en.wikipedia.org/wiki/Triangular_number (Links to an external site.)

Menu

Your program needs to demonstrate all three functions by providing a menu.

The menu should provide user choices to select one of the three functions to call, after prompting user input for function call and the function outputs results, the menu should go back to the first menu to let the user continue choosing functions to call.

If user choose function #1, the menu should prompt the user to enter a string and your program reversely prints the string

Note: Use getline() in standard library so the input takes space characters.

If user chooses function #2, the menu should first prompt the user an integer input for the number of integers in the array, then a series of integers to fill the array. Afterwards, the program prints sum of the array of integers.

If the user chooses function #3, the menu should prompt the user an integer, then the program prints the triangular number of that number.

In addition to the 3 function options inside the first menu, the menu must also provide the option to quit the program. You can add input validation functions into these the menu to make it robust.

File organization

You can put all your recursive functions in a single .cpp file or separate them into different .cpp files. However, you must separate the implementation and declaration in .cpp and .hpp files.

Note: You do not need to make a class for this lab.

What you need to submit

• All the program files including header and source files (.cpp/.hpp)
• Makefile

Important: Put all the files in a single .zip file and submit it on Canvas.

Grading

• Programming style – 10%
• Implement the function to reversely print string – 20%
• Implement the function to calculate the sum of the array – 25%
• Implement the function to calculate the triangular number – 25%
• Implement a program with a menu to call each function or to exit – 20%

Answer 1

Recusrsion.h

#include <iostream>

using namespace std;

void recursiveStringReverse(const string &str);

int recursiveSumOfArrayOfIntegers(int *, int);

int recursiveTriangularNumber(int);

void printMenu();

Recursion.cpp

#include "Recursion.h"

void recursiveStringReverse(const string& str)

{

int numOfChars = str.size();

if(numOfChars == 1)

cout << str << endl;

else

{

cout << str[numOfChars - 1];

recursiveStringReverse(str.substr(0, numOfChars - 1));

}

}

int recursiveSumOfArrayOfIntegers(int *arr, int n)

{

if(n <= 0)

return 0;

return(recursiveSumOfArrayOfIntegers(arr, n - 1) + *(arr + n - 1));

}

int recursiveTriangularNumber(int N)

{

if(N >= 1)

return (N + recursiveTriangularNumber(N - 1));

else

return 0;

}

void printMenu()

{

cout << "1. Reverse a string\n2. Sum of an array of integers\n3. Calculate the triangular number of N\n4. Exit\nEnter your choice: ";

}

main.cpp

#include "Recursion.h"

int main()

{

cout << "\n==================================================";

cout << "\n* Welcome to the program of Recursion *";

cout << "\n==================================================" << endl;

int choice = 0;

do

{

printMenu();

cin >> choice;

cin.ignore();

switch(choice)

{

case 1:

{

string str;

cout << "Input a string to reverse: ";

getline(cin, str);

cout << "Reversed string: ";

recursiveStringReverse(str);

cout << endl;

break;

}

case 2:

{

int N = 0;

cout << "Enter the number of integers in the array: ";

cin >> N;

int *const arr = new int[N];

cout << "Enter the numbers: " << endl;

for(int i = 0; i < N; i++)

{

cin >> *(arr + i);

}

cout << "The sum of all integers in the array: " << recursiveSumOfArrayOfIntegers(arr, N) << endl << endl;

delete [] arr;

break;

}

case 3:

{

int N;

cout << "Enter N for calculating the triangular number: ";

cin >> N;

cout << "The triangular number for N = " << N << " is: " << recursiveTriangularNumber(N) << endl << endl;

break;

}

case 4:

{

cout << endl << "Thank you\nGood Bye!" << endl << endl;

exit(1);

}

default:

cout << endl << "Invalid choice" << endl << endl;

}

}while(choice != 4);

return 0;

}

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