1 files changed, 132 insertions, 0 deletions
diff --git a/future_value4/FutureValue/frmFutureValue.cs b/future_value4/FutureValue/frmFutureValue.cs
new file mode 100644
index 0000000..33f948d
--- /dev/null
+++ b/future_value4/FutureValue/frmFutureValue.cs
@@ -0,0 +1,132 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Data;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace FutureValue
+{
+	public partial class frmFutureValue : Form
+	{
+		public frmFutureValue()
+		{
+			InitializeComponent();
+		}
+
+		private void frmFutureValue_Load(object sender, EventArgs e)
+		{
+			for (int i = 1; i <= 20; ++i)
+				cboYears.Items.Add(i);
+			cboYears.SelectedIndex = 2;
+		}
+
+		private void btnCalculate_Click(object sender, EventArgs e)
+		{
+			try {
+				if (IsValidData()) {
+					lstValues.Items.Clear();
+
+					decimal monthlyInvestment =
+						Convert.ToDecimal(txtMonthlyInvestment.Text);
+					decimal yearlyInterestRate =
+						Convert.ToDecimal(txtInterestRate.Text);
+
+					int years = (int)cboYears.SelectedItem;
+					int months = years * 12;
+					decimal monthlyInterestRate = yearlyInterestRate / 12 / 100;
+
+					for (int i = 1; i <= months; ++i)
+						if (i % 12 == 0) {
+							decimal futureValue = CalculateFutureValue(
+								monthlyInvestment, monthlyInterestRate, i);
+							lstValues.Items.Add("Year " + i/12 + ": "
+								+ futureValue.ToString("c"));
+						}
+				}
+			}
+			catch (Exception ex) {
+				MessageBox.Show(ex.Message + "\n\n" +
+					ex.GetType().ToString() + "\n" +
+					ex.StackTrace, "Exception");
+			}
+		}
+
+		public bool IsValidData()
+		{
+			bool success = true;
+			string errorMessage = "";
+
+			// Validate the Monthly Investment text box
+			errorMessage += IsDecimal(txtMonthlyInvestment.Text, txtMonthlyInvestment.Tag.ToString());
+			errorMessage += IsWithinRange(txtMonthlyInvestment.Text, txtMonthlyInvestment.Tag.ToString(), 1, 1000);
+
+			// Validate the Yearly Interest Rate text box
+			errorMessage += IsDecimal(txtInterestRate.Text, txtInterestRate.Tag.ToString());
+			errorMessage += IsWithinRange(txtInterestRate.Text, txtInterestRate.Tag.ToString(), 1, 20);
+
+			if (errorMessage != "") {
+				success = false;
+				MessageBox.Show(errorMessage, "Entry Error");
+			}
+			return success;
+		}
+
+		public static string IsPresent(string value, string name)
+		{
+			string msg = "";
+			if (value == "") {
+				msg += name + " is a required field.\n";
+			}
+			return msg;
+		}
+
+		public static string IsDecimal(string value, string name)
+		{
+			string msg = "";
+			if (!Decimal.TryParse(value, out _)) {
+				msg += name + " must be a valid decimal value.\n";
+			}
+			return msg;
+		}
+
+		public static string IsInt32(string value, string name)
+		{
+			string msg = "";
+			if (!Int32.TryParse(value, out _)) {
+				msg += name + " must be a valid integer value.\n";
+			}
+			return msg;
+		}
+
+		public static string IsWithinRange(string value, string name, decimal min, decimal max)
+		{
+			string msg = "";
+			if (Decimal.TryParse(value, out decimal number)) {
+				if (number < min || number > max) {
+					msg += name + " must be between " + min + " and " + max + ".\n";
+				}
+			}
+			return msg;
+		}
+
+		private decimal CalculateFutureValue(decimal monthlyInvestment,
+			decimal interestRateMonthly, int months)
+		{
+			decimal futureValue = 0m;
+			for (int i = 0; i < months; i++) {
+				futureValue = (futureValue + monthlyInvestment)
+					* (1 + interestRateMonthly);
+			}
+			return futureValue;
+		}
+
+		private void btnExit_Click(object sender, EventArgs e)
+		{
+			this.Close();
+		}
+	}
+}