Assert dialogs
Question: see book
The source code given for this exercise (with the previous exercise) contains a bug:
the constructor must, of course, have the same name as the class, thus changing
Test () to Adder ()
The same applies to the object creation in the Main method:
new Test() -> new Adder ()
Answer: see 8.4.3 System.Diagnostics.Debug
The modified source code can look like this:
AdderExt2.cs
using System;
using System.Diagnostics;
using System.Windows.Forms;
class Adder : Form {
TextBox amount = new TextBox();
Button b = new Button();
Label total = new Label();
Adder () {
amount.Left = 10; amount.Top = 10;
Controls.Add(amount);
b.Text = "ADD";
b.Left = 10; b.Top = 40;
b.Click += new EventHandler(Add);
Controls.Add(b);
total.Text = "0";
total.Left = 10; total.Top = 70;
Controls.Add(total);
}
void Add (object sender, EventArgs eargs) {
try {
int val = Convert.ToInt32(amount.Text);
Debug.Assert(val >= 0, "Do not enter negative values");
total.Text = (val + Convert.ToInt32(total.Text)).ToString();
} catch (FormatException) {
Debug.Assert(false, "Enter only numbers");
}
}
public static void Main () { Application.Run(new Adder()); }
}
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