Question

Design and implement a C++ program with functions to calculate the pre-tax charge:
If the customer subscribes to a phone plan called Plan200, then he is charged $5 for the first 200 minutes. For each additional minutes, the customer will be charged $0.10.
If the customer subscribes to a phone plan called Max20, then he is charged $0.05 for each minute up to $20. (I.e., the customer never needs to pay more than $20.)
If the customer is not subscribed to any phone plan, then he is charged $0.10 for each minute of the phone calls.

To find out whether and which plan the user is subscribed to, your program can display a message such as:
Please choose one of the following options:
Enter A if you are subscribed to Plan200;
      B if you are subscribed to Max20; or
      any other keys if you are not subscribed to any plan.
Your choice:
And then read the user's input. You can use numbers instead of characters.
You can also choose to give the user a free hand to enter this information, such as:
Please enter the phone plan you are subscribed to
(none if you are not subscribed to any):

Answer 1

#include <iostream>
using namespace std;
//Declaring all the required functions
void Plan200(int min);
void Max20(int min);
void NoPlan(int min);
int main()
{
    int n,min;
    //Displaying the menu for the user
    cout<<"Select Your Plan\nPress 1 for Plan200\nPress 2 for Max20\nPress Any Other Key If You are not Subscribed to any Plan\n";
    //Taking choice Input
    cout<<"Enter Your Choice: ";
    cin>>n;
    //Taking Input of number of Minutes Spoken
    cout<<"Enter Number of Minutes Spoken: ";
    cin>>min;
    //If User Selects 1,Calling Plan200() Function
    if(n==1)
        Plan200(min);
    //IF USer Selects 2,Calling Max20() Function
    else if (n==2)
        Max20(min);
    //Other Than That,Calling NoPlan() Function
    else
        NoPlan(min);
}


//Function for Plan200 Plan
void Plan200(int min){
    //if min less than or equal to 200, charging is $20
    if(min<=200)
        cout<<"You Will Be charged $20 For the First 200 Minutes.";
    else{
        //Calculating total
        double total=20+((min-200)*0.1);
        //printing total
        cout<<"You Will be charged $"<<total;
    }
}


//Function for Max20 Plan
void Max20(int min){
    //Calculating total Bill
    double total=0.05*min;
    //if bill is less than or equal to $20, printing it
    if(total<=20)
        cout<<"You Will be charged $"<<total;
    //else printing $20 as bill
    else
        cout<<"You Will be Charged $20";
}


//Function for No Plan
void NoPlan(int min){
    //Calculating total
    double total=0.1*min;
    //printing the total
    cout<<"You will be charged $"<<total;
}