private void btadd_Click(object sender, EventArgs e)
        {
            try
            {
 
                if (txtscore.Text == "")
                {
                    MessageBox.Show("Score is a required field.", "Entry Error");
                }
                else
                {
                    int score = Convert.ToInt32(txtscore.Text);
                    if (score >= 0 && score <= 100)
                    {
                        int sumav = 0;
                        foreach (int avgscore in scoreTotalArray)
                            sumav += avgscore;
                        int avg = sumav / scoreTotalArray.Length;
 
                        txtscoretotal.Text = score.ToString();
                        //txtscorecount.Text = arraycount.ToString();
                        txtaverage.Text = avg.ToString("d");
 
                        //add scores to array (and update index)
                        scoreTotalArray[scoresIndex] = score;
                        scoresIndex++;
 
                        //add scores to list
                        scoreTotalList.Add(score);
                    }
 
                else
                {
                    MessageBox.Show("Score must be greater than 0 and less than 100.", "Entry Error");
                }
            }
            }
 
            catch (FormatException)
            {
                MessageBox.Show("Please enter a valid number for the Score.", "Entry Error");
            }
 
            catch (IndexOutOfRangeException)
            {
                MessageBox.Show(
                    "The index is out of range. Please exit the application",
                    "Entry Error");
            }
            txtscore.Focus();
        }

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace daniweb.scores
{
  public partial class Form1 : Form
  {
    private List<int> scores;
    public Form1()
    {
      InitializeComponent();
      scores = new List<int>();
    }
 
    private void button1_Click(object sender, EventArgs e)
    {
      errorProvider1.SetError(textBox1, string.Empty);
      int score;
      if (string.IsNullOrEmpty(textBox1.Text))
      {
        errorProvider1.SetError(textBox1, "Please enter a score");
        return;
      }
      if (!int.TryParse(textBox1.Text, out score) || (score < 0) || (score > 100))
      {
        errorProvider1.SetError(textBox1, "You must enter a value between 0 and 100");
        return;
      }
 
 
      AddScore(score);
 
    }
 
    private void AddScore(int score)
    {
      scores.Add(score);
      listBox1.Items.Add(score);
    }
 
    private void DisplayScores()
    {
      scores.Sort();
      listBox1.BeginUpdate();
      listBox1.Items.Clear();
      foreach (int i in scores)
        listBox1.Items.Add(i);
      listBox1.EndUpdate();
    }
 
    private void ClearScores()
    {
      listBox1.Items.Clear();
    }
 
    private void Form1_Load(object sender, EventArgs e)
    {
      ClearScores(); 
    }
 
    private void button2_Click(object sender, EventArgs e)
    {
      int maxScore = scores.Max();
      int minScore = scores.Min();
      double avgScore = scores.Average();
      int cnt = scores.Count;
 
      StringBuilder sb = new StringBuilder();
      sb.AppendLine(string.Format("Max Scores  : {0:F0}", maxScore));
      sb.AppendLine(string.Format("Avg Scores  : {0:F2}", avgScore));
      sb.AppendLine(string.Format("Min Scores  : {0:F0}", minScore));
      sb.AppendLine(string.Format("Total Scores: {0:F0}", cnt));
      MessageBox.Show(sb.ToString());
    }
  }
}