main.cpp

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

void task1();
void task2();
void task3();
void task4();
void reverseArray(int array1[], int arrayLength);//for task 1
int removeDuplicates(int array1[], int arrayLength);//for task 2
void swap(int& num1, int& num2);//for task 4
int mainMenu();

int main() {
    cout << "CS211 Lab 8\nMax Davy\n";
    
    int task = mainMenu();
    while (task > 0 && task < 5) {
        switch (task) {
        case 1:
            task1();
            break;
        case 2:
            task2();
            break;
        case 3:
            task3();
            break;
        case 4:
            task4();
            break;
        }
        task = mainMenu();
    }

    return 0;
}

int mainMenu() {
    cout << "Enter task (1-4). Enter any other number to quit.\n";
    int input;
    cin >> input;
    return input;
}

/*-------------------begin task 1 code-------------------
    Task 1: Write a function which reverses the original array using pointers.
*/

void task1() {
    
    cout << "Task 1:\n";
    int array1[] = { 1,2,3,4,5,6};
    cout << "\tInput array:\n";
    for (int i = 0;i < 6;i++) {
        cout << "\t"<<array1[i] << endl;
    }
    cout << "\tOutput array:\n";
    reverseArray(array1, 6);
    for (int i = 0;i < 6;i++) {
        cout << "\t"<<array1[i] << endl;
    }
}

//for task 1
void reverseArray(int array1[], int arrayLength) {
    int firstItemIndex = 0;
    int secondItemIndex = arrayLength - 1;

    //loop works in pairs moving inwards, e.g. swaps first and last, then second and second to last, etc.
    while (firstItemIndex < secondItemIndex) {//until the middle of the array is reached

        int* firstItemPointer = array1 + firstItemIndex;//get pointer to first item to swap
        int* secondItemPointer = array1 + secondItemIndex;//get pointer to second item to swap

        int temp = *firstItemPointer;//save value at first memory location to temporary variable
        *firstItemPointer = *secondItemPointer;//save value at second memory location to first memory location
        *secondItemPointer = temp;//save temp value (was at first memory location) to second memory location

        firstItemIndex += 1;//move first memory location one item forward
        secondItemIndex -= 1;//move second memory location one item back
    }
}

/*-------------------begin task 2 code-------------------
    Task 2: Write a function to remove duplicates from an ordered array
*/

void task2() {
    
    cout << "Task 2:\n";
    int array1[] = { 1,2,3,3,4,5 };
    cout << "\tInput array:\n";
    for (int i = 0;i < 6;i++) {
        cout << "\t" << array1[i] << endl;
    }
    int length = removeDuplicates(array1, 6);
    cout << "\tOutput array:\n";
    for (int i = 0;i < length;i++) {
        cout << "\t" << array1[i] << endl;
    }
}

//for task 2
int removeDuplicates(int array1[], int arrayLength) {
    bool ordered = false;
    int arrayIndex = 0;//track where we are in the temporary array
    int tempArray[100];//define a temporary array, maximum length function can accept is 100
    for (int i = 0;i < arrayLength;i++) {//go through array
        if (array1[i] != array1[i + 1]) {//if the current array element isn't a duplicate of the one after it
            tempArray[arrayIndex] = array1[i];//add the non-duplicate to the temporary array
            arrayIndex++;//increment position in temp array
        }
    }
    for (int i = 0;i < arrayIndex;i++) {//save temporary array values back to the first array
        array1[i] = tempArray[i];
    }
    return arrayIndex;//return length of new array
}

/*-------------------begin task 3 code-------------------
    Task 3: Write a program to find the GCD and LCM of two numbers 
    (you may need to reread how to find GCD and LCM if you have forgotten it)
*/

void task3() {
    
    cout << "Task 3:\n";
    int number1;
    int number2;
    cout << "\tPlease enter first number:\n";
    cin >> number1;
    cout << "\tPlease enter second number:\n";
    cin >> number2;

    //find lcm
    bool divisible = false;
    int multiple = (number1 > number2) ? number1 : number2;//set multiple to the greater of the two numbers
    while (!divisible) {//as long as the last checked multiple was not divisible
        multiple++;//increment multiple
        divisible = (multiple % number1 == 0) && (multiple % number2 == 0);//check if multiple is divisible evenly by both numbers
    }
    cout << "\tLeast Common Multiple of " << number1 << " and " << number2 << " is " << multiple << endl;
    //find gcd
    divisible = false;
    multiple = (number1 > number2) ? number2 : number1;//set multiple to the lesser of the two numbers
    while (!divisible) {//as long as the last checked multiple was not divisible
        multiple--;//decrement multiple
        divisible = (number1%multiple == 0) && (number2%multiple == 0);//check if multiple is divisible evenly by both numbers
    }
    cout << "\tGreatest Common Divisor of " << number1 << " and " << number2 << " is " << multiple << endl;
}

/*-------------------begin task 4 code------------------
    Task 4: Implement a swap() function that exchanges the values of two integers.
    Call the function from the main function to test the function with different values.
*/

void task4() {
    
    int num1;
    int num2;
    cout << "Task 4:\n";
    cout << "\tEnter first number:\n";
    cin >> num1;
    cout << "\tEnter second number:\n";
    cin >> num2;
    swap(num1, num2);
    cout << "\tSwapping numbers...\n";
    cout << "\tFirst number is now " << num1 << endl;
    cout << "\tSecond number is now " << num2 << endl;
}

//for task 4
void swap(int& num1, int& num2) {
    int temp = num1;
    num1 = num2;
    num2 = temp;
}