Simple programs 8 to 18

// Simple Programs

#include <iostream>
using namespace std;

// Hello world

void helloWorld()
{

    cout << "Hello World" << endl;
}

// addition if two integer numbers

void addInt()
{
    int a, b, sum;
    cout << "Enter two Integer numbers :" << endl;
    cin >> a >> b;
    sum = a + b;
    cout << "Sum of two intergers is :" << sum << endl;
}

// addition of two float numbers

void addFloat()
{
    float a, b, sum;
    cout << "Enter two Float numbers :" << endl;
    cin >> a >> b;
    sum = a + b;
    cout << "Sum of two float numbers is :" << sum << endl;
}

// average of two integers

void avgInt()
{
    int a, b, avg;
    cout << "Enter numbers to find Average :" << endl;
    cin >> a >> b;
    avg = (a + b) / 2;
    cout << "Average is :" << avg << endl;
}

// average of two float numbers

void avgFloat()
{
    float a, b, avg;
    cout << "Enter float numbers to find average :" << endl;
    cin >> a >> b;
    avg = (a + b) / 2;
    cout << "Average is :" << avg;
}

// average marks scored in five subjects

void avgMarks()
{

    float a, b, c, d, e, f, avg;
    cout << "Enter marks scored in Maths :" << endl;
    cin >> a;
    cout << "Enter marks scored in Physics :" << endl;
    cin >> b;
    cout << "Enter marks scored in  English :" << endl;
    cin >> c;
    cout << "Enter marks scored in Sceince :" << endl;
    cin >> d;
    cout << "Enter marks scored in Hindi :" << endl;
    cin >> e;
    avg = (a + b + c + d + e) / 5;
    cout << "Average is : " << avg;
}
// exchange value of 2 variables using a third variable

void exchVar1()
{
    int a = 5, b = 10, temp;
    cout << "Before swapping a = " << a << "& b = " << b << endl;
    temp = a; // here, temp = 5
    a = b;    // here, a = 10
    b = temp; // now b = 5
    cout << "After swapping a = " << a << "& b = " << b << endl;
}
// exachange value of two variables without using a third variable
void exchVar2()
{
    int a = 10, b = 20;
    cout << "Before swapping a = " << a << " & b = " << b << endl;
    a = a + b; // here a = 10+20 i.e 30
    b = a - b; // here b = 30-20 i.e 10
    a = a - b; // here a = 30-10 i.e 20
    cout << "After swapping a = " << a << " & b = " << b << endl;
}

// convert temperature from fahrenheit to celsius

void temp_F_to_C()
{
    float f, c;
    cout << "Enter Temperature in Fahrenheit : " << endl;
    cin >> f;
    c = (f - 32) * 5 / 9;
    cout << "Temperature in Celsius is : " << c << endl;
}

// convert temperature from celsius to fahrenheit

void temp_C_to_F()
{
    float f, c;
    cout << "Enter Temperature in Celsius : " << endl;
    cin >> c;
    f = ((c * 9) / 5 + 32);
    cout << "Temperature in Fahrenheit is : " << f << endl;
}

// find area of circle

void areaofCircle()
{
    float r;
    cout << "Enter the radius to find area of circle : " << endl;
    cin >> r;
    r = 3.142 * r * r;
    cout << "Area is : " << r << endl;
}
// ????????reverse of a 5 digit number????????
// void reverseNum()
// {
//     int num, rem, rev = 0;
//     cout <<"Enter number to find it's reverse : "<<endl;
//       //eg; num = 123 i.e !=0
//         rem = num % 10; // num = 123 % 10 => rem = 3
//         rev = rem + (rev*10); // rev = 3 + (0*10) => 3 so, rev = 3
//         num = num / 10; // num = 123 / 10 => 12
// if(num!=0){
//     cout <<"Reverse is : "<<rev<<endl;
// }

// }
// ??????????????????

//????????????find sum of all digits of a five digit number??????????

// void revFiveDigitNum() 
// {

// }
//????????????????????????
int main()
{
    // Total listed programs
    cout << "-+-+-+-+->   All Programs : Part - 1   <-+-+-+-+-" << endl;
    cout << endl;

    cout << "Enter 1 to print Hello World in c++ : " << endl;
    cout << "Enter 2 to find addition of two integer numbers : " << endl;
    cout << "Enter 3 to find adddition of two float numbers : " << endl;
    cout << "Enter 4 to find average of two integer numbers : " << endl;
    cout << "Enter 5 to find average of two float numbers : " << endl;
    cout << "Enter 6 to find average marks of a student in five subjects : " << endl;
    cout << "Enter 7 to exchange values of two variables - using third variable " << endl;
    cout << "Enter 8 to exchange values of two variables - without using third variable : " << endl;
    cout << "Enter 9 to convert - Temperature C to F : " << endl;
    cout << "Enter 10 to connvert - Temperature F to C : " << endl;
    cout << "Enter 11 to find area of a circle :" << endl;
    cout << "Enter 12 to find reverse of a number (five-digit number) : " << endl;
    cout << "Enter 13 to find the sum of all digits (five-digit number) : " << endl;

    cout << endl;

    int count;
    cout << "Enter the program number, that you want to execute : ";
    cin >> count;

    switch (count)
    {
    case 1:
        helloWorld();
        break;

    case 2:
        addInt();
        break;

    case 3:
        addFloat();
        break;

    case 4:
        avgInt();
        break;

    case 5:
        avgFloat();
        break;

    case 6:
        avgMarks();
        break;

    case 7:
        exchVar1();
        break;

    case 8:
        exchVar2();
        break;

    case 9:
        temp_F_to_C();
        break;

    case 10:
        temp_C_to_F();
        break;

    case 11:
        areaofCircle();
        break;

    case 12:
//revFiveDigitNum();
        break;

    case 13:
//sumFiveDigitNum();
        break;


    return 0;
  }
}