In this C# tutorial, I will teach you how to create a program that will compute sum, difference, quotient, and product as just a simple calculator that uses a class.

Now, let's start this tutorial!

1. Let's start with creating a Windows Form Application in C# for this tutorial by following the following steps in Microsoft Visual Studio: Go to File, click New Project, and choose Windows Application.

2. Next, add one TextBox named TextBox1 for inputting first number, Textbox2 for inputting second number, and Textbox3 for displaying the total.Insert also 4 RadioButton named Radio_Addition for addition operation, Radio_Subtraction for subtraction operation, Radio_Division for division operation and Radio_Multiplication for multiplication operation. You must design your layout like this:



3. Create a class named calculate and put this code below.

1. using
   
   System.Diagnostics
   
   ;
   
2. using
   
   System
   
   ;
   
3. using
   
   System.Xml.Linq
   
   ;
   
4. using
   
   System.Windows.Forms
   
   ;
   
5. using
   
   System.Collections
   
   ;
   
6. using
   
   System.Drawing
   
   ;
   
7. using
   
   System.Data
   
   ;
   
8. using
   
   System.Collections.Generic
   
   ;
   
9. using
   
   System.Linq
   
   ;
   
10. 
    
11. 
    
12. namespace
    
    MDAS
    
13. {
    
14. public
    
    class
    
    calculate
    
15. {
    
16. //declare a private variable as a double
    
17. private
    
    double
    
    _num1;
    
18. private
    
    double
    
    _num2;
    
19. private
    
    double
    
    _total;
    
20. 
    
21. //set a readonly property for the total of the MDAS
    
22. public
    
    double
    
    total
    
23. {
    
24. get
    
25. {
    
26. return
    
    _total;
    
    //return the total
    
27. }
    
28. }
    
29. //create a property for a private variable so that you can access it
    
30. public
    
    double
    
    num1
    
31. {
    
32. get
    
33. {
    
34. return
    
    _num1;
    
    //return the first value
    
35. }
    
36. set
    
37. {
    
38. _num1 =
    
    value
    
    ;
    
    //set the first value
    
39. }
    
40. }
    
41. public
    
    double
    
    num2
    
42. {
    
43. get
    
44. {
    
45. return
    
    _num2;
    
46. }
    
47. set
    
48. {
    
49. _num2 =
    
    value
    
    ;
    
50. }
    
51. }
    
52. 
    
53. //create the sub procedures of the MDAS
    
54. public
    
    void
    
    multiply(
    
    )
    
55. {
    
56. //formula of multiplication
    
57. _total =
    
    num1 *
    
    num2;
    
58. }
    
59. public
    
    void
    
    divide(
    
    )
    
60. {
    
61. //formula of division
    
62. _total =
    
    num1 /
    
    num2;
    
63. }
    
64. public
    
    void
    
    add
    
    (
    
    )
    
65. {
    
66. //formula of addition
    
67. _total =
    
    num1 +
    
    num2;
    
68. }
    
69. public
    
    void
    
    subtract(
    
    )
    
70. {
    
71. //formula of subtraction
    
72. _total =
    
    num1 -
    
    num2;
    
73. }
    
74. 
    
75. 
    
76. }
    
77. 
    
78. }
    

4. Now, go to your Form and put this code below for the calculator operation.

1. using
   
   System.Diagnostics
   
   ;
   
2. using
   
   System
   
   ;
   
3. using
   
   System.Xml.Linq
   
   ;
   
4. using
   
   System.Windows.Forms
   
   ;
   
5. using
   
   System.Collections
   
   ;
   
6. using
   
   System.Drawing
   
   ;
   
7. using
   
   System.Data
   
   ;
   
8. using
   
   System.Collections.Generic
   
   ;
   
9. using
   
   System.Linq
   
   ;
   
10. 
    
11. 
    
12. 
    
13. namespace
    
    MDAS
    
14. {
    
15. public
    
    partial
    
    class
    
    Form1
    
16. {
    
17. public
    
    Form1(
    
    )
    
18. {
    
19. InitializeComponent(
    
    )
    
    ;
    
20. }
    
21. 
    
22. //create a sub procedure for the events of clicking the radio button that handles all of it.
    
23. public
    
    void
    
    RadioButton_Click(
    
    object
    
    sender, System
    
    .
    
    EventArgs
    
    e)
    
24. {
    
25. 
    
26. //call a constructor method and return to cal as an instance of a class
    
27. calculate cal =
    
    new
    
    calculate(
    
    )
    
    ;
    
28. 
    
29. //declaring the string variable represent as a textbox
    
30. string
    
    txtnum1 =
    
    TextBox1.
    
    Text
    
    ;
    
31. string
    
    txtnum2 =
    
    TextBox2.
    
    Text
    
    ;
    
32. //declaring the double variable
    
33. double
    
    dbl_val1 =
    
    default
    
    (
    
    double
    
    )
    
    ;
    
34. double
    
    dbl_val2 =
    
    default
    
    (
    
    double
    
    )
    
    ;
    
35. 
    
36. if
    
    (
    
    Information.
    
    IsNumeric
    
    (
    
    txtnum1)
    
    &&
    
    Information.
    
    IsNumeric
    
    (
    
    txtnum2)
    
    )
    
    //check if the textbox has a numeric value
    
37. {
    
38. //convert the string to double
    
39. dbl_val1 =
    
    double
    
    .
    
    Parse
    
    (
    
    txtnum1)
    
    ;
    
40. dbl_val2 =
    
    double
    
    .
    
    Parse
    
    (
    
    txtnum2)
    
    ;
    
41. 
    
42. //get the value of the converted variable
    
43. //to pass it into the variable in the class
    
44. cal.
    
    num1
    
    =
    
    dbl_val1;
    
45. cal.
    
    num2
    
    =
    
    dbl_val2;
    
46. 
    
47. //the condition is, if the radiobutton is clicked,
    
48. //the operation of MDAS executes.
    
49. if
    
    (
    
    Radio_Multiplication.
    
    Checked
    
    )
    
50. {
    
51. //result:
    
52. cal.
    
    multiply
    
    (
    
    )
    
    ;
    
    //call a subname in a class for multiplying
    
53. }
    
54. else
    
    if
    
    (
    
    Radio_Division.
    
    Checked
    
    )
    
55. {
    
56. //result:
    
57. cal.
    
    divide
    
    (
    
    )
    
    ;
    
    //call a subname in a class for dividing
    
58. }
    
59. else
    
    if
    
    (
    
    Radio_Addition.
    
    Checked
    
    )
    
60. {
    
61. //result:
    
62. cal.
    
    add
    
    (
    
    )
    
    ;
    
    //call a subname in a class for adding
    
63. }
    
64. else
    
    if
    
    (
    
    Radio_Subtaction.
    
    Checked
    
    )
    
65. {
    
66. //result:
    
67. cal.
    
    subtract
    
    (
    
    )
    
    ;
    
    //call a subname in a class for subtracting
    
68. }
    
69. }
    
70. else
    
71. {
    
72. //the result is:
    
73. //if the textbox is empty or has a string value
    
74. TextBox3.
    
    Text
    
    =
    
    "Enter a number"
    
    ;
    
75. return
    
    ;
    
76. }
    
77. //put the result of the MDAS to a textbox.
    
78. TextBox3.
    
    Text
    
    =
    
    cal.
    
    total
    
    .
    
    ToString
    
    (
    
    )
    
    ;
    
79. }
    
80. 
    
81. 
    
82. }
    
83. 
    
84. }
    

Output:


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Best Regards,

Engr. Lyndon Bermoy
IT Instructor/System Developer/Android Developer/Freelance Programmer

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