C＃如何计算在开关循环中找到平均值的输入数量？

Question

Here is my loop that asks for the group number then the donation. I'm wondering how to count the number of donations to find the average for each group.

using System;
public class TotalPurchase
{
    public static void Main()
    {

    double total4 = 0;
    double total5 = 0;
    double total6 = 0;
    int myint = -1;

    while (myint != 0)
    {
        string group;

        Console.WriteLine("Please enter group number (4, 5, or 6)");
        Console.WriteLine("(0 to quit): ");
        group = Console.ReadLine();
        myint = Int32.Parse(group);

        switch (myint)
        {
            case 0:
                break;
            case 4:
                double donation4;
                string inputString4;
                Console.WriteLine("Please enter the amount of the contribution: ");
                inputString4 = Console.ReadLine();
                donation4 = Convert.ToDouble(inputString4);
                total4 += donation4;
                break;
            case 5:
                double donation5;
                string inputString5;
                Console.WriteLine("Please enter the amount of the contribution: ");
                inputString5 = Console.ReadLine();
                donation5 = Convert.ToDouble(inputString5);
                total5 += donation5;
                break;
            case 6:
                double donation6;
                string inputString6;
                Console.WriteLine("Please enter the amount of the contribution: ");
                inputString6 = Console.ReadLine();
                donation6 = Convert.ToDouble(inputString6);
                total6 += donation6;
                break;
            default:
                Console.WriteLine("Incorrect grade number.", myint);
                break;
        }
    }

    Console.WriteLine("Grade 4 total is {0}", total4.ToString("C"));
    Console.WriteLine("Grade 5 total is {0}", total5.ToString("C"));
    Console.WriteLine("Grade 6 total is {0}", total6.ToString("C"));

    }
}

Any help would be appreciated.

Answer 1

Not sure if I fully understand your question -- but you could just add a simple counter for each group:

int donations4 = 0;
int donations5 = 0;
int donations6 = 0;

And then increment that counter in each of your switch cases, ex:

switch(myInt)
{
   case 4:
     ...
     donations4++;
     break;
   case 5:
     ...
     donations5++;
     break;
   case 6:
     ...
     donations6++;
     break;
}

Then when you're done - simply do the math to find the average.

Although this is probably the simplest way, a better way would be to treat each group as its own object, and have the object internally track the # of donations, as well as the sum and average.

-- Dan

Answer 2

Just declare count for each group as well as total and increment in the case statement:

case 4:
            double donation4;
            string inputString4;
            Console.WriteLine("Please enter the amount of the contribution: ");
            inputString4 = Console.ReadLine();
            donation4 = Convert.ToDouble(inputString4);
            total4 += donation4;
            count4++; // HERE!!!!
            break;

Alternatively, you can use List<int> which will calculate your average as well:

 List<int> list4 = new List<int>();

and

case 4:
            double donation4;
            string inputString4;
            Console.WriteLine("Please enter the amount of the contribution: ");
            inputString4 = Console.ReadLine();
            donation4 = Convert.ToDouble(inputString4);
            list4.Add(donation4);
            break;

and

 Console.WriteLine(list4.Average());

Answer 3

Just keep track of the count yourself with another variable. count4 , count5 , etc.

Answer 4

using System;

public class TotalPurchase
{
    public static void Main()
    {
       double total4 = 0;
       double total5 = 0;
       double total6 = 0;

       int numberOfInputForTotal4 = 0;
       int numberOfInputForTotal5 = 0;
       int numberOfInputForTotal6 = 0;

       int myint = -1;

        while (myint != 0)
        {
            string group;

            Console.WriteLine("Please enter group number (4, 5, or 6)");
            Console.WriteLine("(0 to quit): ");
            group = Console.ReadLine();
            myint = Int32.Parse(group);

            switch (myint)
            {
                case 0:
                    break;
                case 4:
                    double donation4;
                    string inputString4;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString4 = Console.ReadLine();
                    donation4 = Convert.ToDouble(inputString4);
                    total4 += donation4;
                    numberOfInputForTotal4++;
                    break;
                case 5:
                    double donation5;
                    string inputString5;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString5 = Console.ReadLine();
                    donation5 = Convert.ToDouble(inputString5);
                    total5 += donation5;
                    numberOfInputForTotal5++;
                    break;
                case 6:
                    double donation6;
                    string inputString6;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString6 = Console.ReadLine();
                    donation6 = Convert.ToDouble(inputString6);
                    total6 += donation6;
                    numberOfInputForTotal6++;
                    break;
                default:
                    Console.WriteLine("Incorrect grade number.", myint);
                    break;
            }
        }

        Console.WriteLine("Grade 4 total is {0}", total4.ToString("C"));
        Console.WriteLine("Grade 5 total is {0}", total5.ToString("C"));
        Console.WriteLine("Grade 6 total is {0}", total6.ToString("C"));

        Console.WriteLine("Grade 4 average is {0}", (total4 / numberOfInputForTotal4).ToString("C"));
        Console.WriteLine("Grade 5 average is {0}", (total5 / numberOfInputForTotal5).ToString("C"));
        Console.WriteLine("Grade 6 average is {0}", (total6 / numberOfInputForTotal6).ToString("C"));

    }
}

As you can see, there are 3 extra variables (one for each group) that can be used to figure out the number of inputs provided. Using that you can divide the total for each group by the number of input in each group separately.

Answer 5

For bonus points in your homework assignment:

1) Sanitize your group number input - ie check to see if the user typed in a valid number.

2) Don't call the variable myInt. Call it groupNum, or something that describes the function, not the implementation of the variable.

3) Use an array for donation totals and counts ie,

int[] donationCount= new int[MAX_GROUP+1];    // figure out yourself why the +1
int[] donationTotal= new int[MAX_GROUP+1];
// initialize donationCount and donationTotal here

then in your loop (don't even need switch):

++donationCount[groupNum];
donationTotal[groupNum] += donationAmount;    // did you notice that you moved the reading of donationAmount out of the switch?

Answer 6

I would go with changing your doubles to List and using the Sum() and Average() methods on your Lists at the end. Your code would look like this after this change.

    using System;
using System.Collections.Generic;
using System.Linq;
public class TotalPurchase
{
    public static void Main()
    {

        List<double> total4 = new List<double>();
        List<double> total5 = new List<double>();
        List<double> total6 = new List<double>();
        int myint = -1;

        while (myint != 0)
        {
            string group;

            Console.WriteLine("Please enter group number (4, 5, or 6)");
            Console.WriteLine("(0 to quit): ");
            group = Console.ReadLine();
            myint = Int32.Parse(group);

            switch (myint)
            {
                case 0:
                    break;
                case 4:
                    double donation4;
                    string inputString4;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString4 = Console.ReadLine();
                    donation4 = Convert.ToDouble(inputString4);
                    total4.Add(donation4);
                    break;
                case 5:
                    double donation5;
                    string inputString5;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString5 = Console.ReadLine();
                    donation5 = Convert.ToDouble(inputString5);
                    total5.Add(donation5);
                    break;
                case 6:
                    double donation6;
                    string inputString6;
                    Console.WriteLine("Please enter the amount of the contribution: ");
                    inputString6 = Console.ReadLine();
                    donation6 = Convert.ToDouble(inputString6);
                    total6.Add(donation6);
                    break;
                default:
                    Console.WriteLine("Incorrect grade number.", myint);
                    break;
            }
        }

        if(total4.Count > 0)
            Console.WriteLine("Grade 4 total is {0}; Average {1}", total4.Sum().ToString("C"), total4.Average().ToString("C"));
        if(total5.Count >0)
            Console.WriteLine("Grade 5 total is {0}; Average {1}", total5.Sum().ToString("C"), total5.Average().ToString("C"));
        if (total6.Count > 0)
            Console.WriteLine("Grade 6 total is {0}; Average {1}", total6.Sum().ToString("C"), total6.Average().ToString("C"));

    }
}