Question

Create a windows form application in C# that looks and functions like a basic calculator. It must do the following:

1. Add, subtract, multiply, and divide.
2. Account for division by zero.
3. Show at least two decimal places.
4. Retain the last number on the window so that, when the user opens the calculator the next time, the number that was in the window at the last close appears.
5. Have a memory, so that users can store values and recall them.
6. Operate with a mouse clicking buttons
7. Operate from the keyboard only with no mouse requirement.
8. Contain a small box for a company logo. Make up a logo and insert it there.
9. Contain a clear and clear all button.
10. The user must not be able to enter data directly in the display window – they have to press the keys.
11. Look like a calculator, and not a maximized window.
12. Use naming conventions for all the elements on the form. In other words, do not use the default names for the labels, buttons, or other controls.

Answer 1

1. using System;  
2. using System.Collections.Generic;  
3. using System.Component Model;  
4. using System.Data;  
5. using System.Drawing;  
6. using System.Text;  
7. using System.Windows.Forms;  
8.   
9. namespace Calculator
10. {  
11.     public partial class Form1 : Form  
12.     {  
13.         double FirstNumber;  
14.         string Operation;  
15.         public Form1()  
16.         {  
17.             InitializeComponent();  
18.         }  
19.   
20.          
21.         private void n1_Click(object sender, EventArgs e)  
22.         {  
23.             if (textBox1.Text == "0" && textBox1.Text != null)  
24.             {  
25.                 textBox1.Text = "1";  
26.             }  
27.             else  
28.             {  
29.                 textBox1.Text = textBox1.Text + "1";  
30.             }  
31.         }  
32.   
33.         private void n2_Click(object sender, EventArgs e)  
34.         {  
35.             if (textBox1.Text == "0" && textBox1.Text != null)  
36.             {  
37.                 textBox1.Text = "2";  
38.             }  
39.             else  
40.             {  
41.                 textBox1.Text = textBox1.Text + "2";  
42.             }  
43.         }  
44.   
45.         private void n3_Click(object sender, EventArgs e)  
46.         {  
47.             if (textBox1.Text == "0" && textBox1.Text != null)  
48.             {  
49.                 textBox1.Text = "3";  
50.             }  
51.             else  
52.             {  
53.                 textBox1.Text = textBox1.Text + "3";  
54.             }  
55.         }  
56.   
57.         private void n4_Click(object sender, EventArgs e)  
58.         {  
59.             if (textBox1.Text == "0" && textBox1.Text != null)  
60.             {  
61.                 textBox1.Text = "4";  
62.             }  
63.             else  
64.             {  
65.                 textBox1.Text = textBox1.Text + "4";  
66.             }  
67.         }  
68.   
69.         private void n5_Click(object sender, EventArgs e)  
70.         {  
71.             if (textBox1.Text == "0" && textBox1.Text != null)  
72.             {  
73.                 textBox1.Text = "5";  
74.             }  
75.             else  
76.             {  
77.                 textBox1.Text = textBox1.Text + "5";  
78.             }  
79.         }  
80.   
81.         private void n6_Click(object sender, EventArgs e)  
82.         {  
83.             if (textBox1.Text == "0" && textBox1.Text != null)  
84.             {  
85.                 textBox1.Text = "6";  
86.             }  
87.             else  
88.             {  
89.                 textBox1.Text = textBox1.Text + "6";  
90.             }  
91.         }  
92.   
93.         private void n7_Click(object sender, EventArgs e)  
94.         {  
95.             if (textBox1.Text == "0" && textBox1.Text != null)  
96.             {  
97.                 textBox1.Text = "7";  
98.             }  
99.             else  
100.             {  
101.                 textBox1.Text = textBox1.Text + "7";  
102.             }  
103.         }  
104.   
105.         private void n8_Click(object sender, EventArgs e)  
106.         {  
107.             if (textBox1.Text == "0" && textBox1.Text != null)  
108.             {  
109.                 textBox1.Text = "8";  
110.             }  
111.             else  
112.             {  
113.                 textBox1.Text = textBox1.Text + "8";  
114.             }  
115.         }  
116.   
117.         private void n9_Click(object sender, EventArgs e)  
118.         {  
119.             if (textBox1.Text == "" && textBox1.Text != null)  
120.             {  
121.                 textBox1.Text = "9";  
122.             }  
123.             else  
124.             {  
125.                 textBox1.Text = textBox1.Text + "9";  
126.             }  
127.         }  
128.   
129.         private void n0_Click(object sender, EventArgs e)  
130.         {  
131.             textBox1.Text = textBox1.Text + "0";  
132.         }  
133.   
134.         private void bad_Click(object sender, EventArgs e)  
135.         {  
136.             FirstNumber = Convert.ToDouble(textBox1.Text);  
137.             textBox1.Text = "0";  
138.             Operation = "+";  
139.         }  
140.   
141.         private void bsub_Click(object sender, EventArgs e)  
142.         {  
143.             FirstNumber = Convert.ToDouble(textBox1.Text);  
144.             textBox1.Text = "0";  
145.             Operation = "-";  
146.   
147.         }  
148.   
149.         private void bmul_Click(object sender, EventArgs e)  
150.         {  
151.             FirstNumber = Convert.ToDouble(textBox1.Text);  
152.             textBox1.Text = "0";  
153.             Operation = "*";  
154.         }  
155.   
156.         private void bdiv_Click(object sender, EventArgs e)  
157.         {  
158.             FirstNumber = Convert.ToDouble(textBox1.Text);  
159.             textBox1.Text = "0";  
160.             Operation = "/";  
161.         }  
162.   
163.         private void bc_Click(object sender, EventArgs e)  
164.         {  
165.             textBox1.Text = "0";  
166.         }  
167.   
168.         private void ndot_Click(object sender, EventArgs e)  
169.         {  
170.             textBox1.Text = textBox1.Text + ".";  
171.         }  
172.   
173.         private void nequal_Click(object sender, EventArgs e)  
174.         {  
175.             double SecondNumber;  
176.             double Result;  
177.   
178.             SecondNumber = Convert.ToDouble(textBox1.Text);  
179.   
180.             if (Operation == "+")  
181.             {  
182.                 Result = (FirstNumber + SecondNumber);  
183.                 textBox1.Text = Convert.ToString(Result);  
184.                 FirstNumber = Result;  
185.             }  
186.             if (Operation == "-")  
187.             {  
188.                 Result = (FirstNumber - SecondNumber);  
189.                 textBox1.Text = Convert.ToString(Result);  
190.                 FirstNumber = Result;  
191.             }  
192.             if (Operation == "*")  
193.             {  
194.                 Result = (FirstNumber * SecondNumber);  
195.                 textBox1.Text = Convert.ToString(Result);  
196.                 FirstNumber = Result;  
197.             }  
198.             if (Operation == "/")  
199.             {  
200.                 if (SecondNumber == 0)  
201.                 {  
202.                     textBox1.Text = "Cannot divide by zero";  
203.   
204.                 }  
205.                 else  
206.                 {  
207.                     Result = (FirstNumber / SecondNumber);  
208.                     textBox1.Text = Convert.ToString(Result);  
209.                     FirstNumber = Result;  
210.                 }  
211.             }  
212.         }
213.     }  
214. }