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PODIsplaying a message in an exception
 

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    <p>I wrote some code testing out a BankAccount and I finished it (for the most part). The purpose was me attempting to learn how to throw and try/catch exceptions. For the most part I learned quite a bit. I realize this wasn't an "exceptional" case and if/else statements would have been more appropriate. I am just trying to learn exception handling. I am trying to write the exception classes to extend a class to include a new message detailing the error being sent when an exception is thrown. I read up on what a super class is, or base class in c#, and tried it. It compiles and looks right but I don't know what I am doing wrong. Can someone explain to me why my message in my throw new NegativeDepositException will not show.</p> <p>What I would like for it to do, is to throw a message instead of me putting a string in MessageBox.Show.</p> <pre><code>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 WindowsFormsApplication2 { public partial class Form1 : Form { public class NegativeBalanceException : Exception { } public class NegativeWithdrawException : Exception { } public class NegativeDepositException : Exception { public NegativeDepositException() { } // this doesn't do what I would like for it to do. public NegativeDepositException(string message) : base(message) { } } public Form1() { InitializeComponent(); } public class BankAccount { decimal amount = 300.00m; // Declare Delegate Type Object public delegate void BankDelegate(decimal oldBalance, decimal newBalance); // Create Delegate Type Events public event BankDelegate OnDeposit; public event BankDelegate OnWithdraw; public void Deposit(decimal a) { if (a &lt; 0) throw new NegativeDepositException(); //"type some message here instead of messagebox below"); OnDeposit(this.amount, this.amount + a); this.amount += a; } public void Withdraw(decimal a) { if (a &lt; 0) throw new NegativeWithdrawException(); OnWithdraw(this.amount, this.amount - a); this.amount -= a; if (this.amount &lt; 0) throw new NegativeBalanceException(); } } // this is my bank class variable... BankAccount account = null; private void Form1_Load(object sender, EventArgs e) { account = new BankAccount(); account.OnDeposit += new BankAccount.BankDelegate(account_OnDeposit); account.OnWithdraw += new BankAccount.BankDelegate(account_OnWithdraw); } private void btnDeposit_Click(object sender, EventArgs e) { { var amount = Convert.ToDecimal(textBox1.Text); try { account.Deposit(amount); } catch (NegativeDepositException) { MessageBox.Show("Cannot deposit negative amounts"); } } } private void btnWIthdraw_Click(object sender, EventArgs e) { var amount = Convert.ToDecimal(textBox1.Text); try { account.Withdraw(amount); } catch (NegativeBalanceException) { MessageBox.Show("Cannot withdraw money that isn't there"); } catch (NegativeWithdrawException) { MessageBox.Show("Cannot withdraw negative money"); } } void account_OnDeposit(decimal oldBalance, decimal newBalance) { label4.Text = oldBalance.ToString(); label5.Text = newBalance.ToString(); } void account_OnWithdraw(decimal oldBalance, decimal newBalance) { label4.Text = oldBalance.ToString(); label5.Text = newBalance.ToString(); } } </code></pre>
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