Visual F# 100 Examples: Example Number 4

Problem: Make an application that will display the area of an annulus (overlapping circles). The area of an annulus can be calculated by subtracting the area of a small circle from the area of a larger circle.

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1. // Learn more about F# at http://fsharp.net  
2. //specifies the memory location of the class files  
3. //that will be needed in our application  
4. open System.Collections.Generic  
5. open System  
6. open System.Windows.Forms  
7. open System.ComponentModel  
8. open System.Drawing  
9. //creates a new form  
10. let annulform=new Form(Text="Dislay the Area of an Annulus", Size=new System.Drawing.Size(300, 200),StartPosition=FormStartPosition.CenterScreen,AutoScaleMode=AutoScaleMode.Font)  
11. //creates our controls  
12. let n1label=new Label(Text="Area of a large circle:",Location=new System.Drawing.Point(0,20),AutoSize=true)  
13. let firsttextbox=new TextBox(Location=new System.Drawing.Point(120, 20))  
14. let n2label=new Label(Text="Area of a small circle:", Location=new System.Drawing.Point(0,50),AutoSize=true)  
15. let secondtextbox=new TextBox(Location=new System.Drawing.Point(120,50))  
16. let n3label=new Label(Text="Area of an annulus:", Location=new System.Drawing.Point(0, 90),AutoSize=true)  
17. //creates a label that will display the result of the computation  
18. let anslabel=new Label(Location=new System.Drawing.Point(120, 90), BorderStyle=BorderStyle.FixedSingle)  
19. //make our buttons  
20. let computebutton=new Button(Text="Compute", Location=new System.Drawing.Point(100, 130))  
21. let exitbutton=new Button(Text="Exit", Location=new System.Drawing.Point(200, 130))  
22. //add the controls into the form  
23. annulform.Controls.Add(n1label)  
24. annulform.Controls.Add(firsttextbox)  
25. annulform.Controls.Add(n2label)  
26. annulform.Controls.Add(secondtextbox)  
27. annulform.Controls.Add(n3label)  
28. annulform.Controls.Add(anslabel)  
29. annulform.Controls.Add(computebutton)  
30. annulform.Controls.Add(exitbutton)  
31.   
32. //when the compute button is clicked  
33. computebutton.Click.Add(fun ans ->  
34. let areaoflargecircle=Convert.ToDouble(firsttextbox.Text)  
35. let areaofsmallcircle=Convert.ToDouble(secondtextbox.Text)  
36. let areaofannulus=areaoflargecircle-areaofsmallcircle  
37.   
38. //display the area of annulus value in the anslabel  
39. anslabel.Text<-Convert.ToString(areaofannulus))  
40.  //when the exit button is clicked, close the form              
41. exitbutton.Click.Add(fun exit -> annulform.Close())    
42. Application.Run(annulform)  

// Learn more about F# at http://fsharp.net
//specifies the memory location of the class files
//that will be needed in our application
open System.Collections.Generic
open System
open System.Windows.Forms
open System.ComponentModel
open System.Drawing
//creates a new form
let annulform=new Form(Text="Dislay the Area of an Annulus", Size=new System.Drawing.Size(300, 200),StartPosition=FormStartPosition.CenterScreen,AutoScaleMode=AutoScaleMode.Font)
//creates our controls
let n1label=new Label(Text="Area of a large circle:",Location=new System.Drawing.Point(0,20),AutoSize=true)
let firsttextbox=new TextBox(Location=new System.Drawing.Point(120, 20))
let n2label=new Label(Text="Area of a small circle:", Location=new System.Drawing.Point(0,50),AutoSize=true)
let secondtextbox=new TextBox(Location=new System.Drawing.Point(120,50))
let n3label=new Label(Text="Area of an annulus:", Location=new System.Drawing.Point(0, 90),AutoSize=true)
//creates a label that will display the result of the computation
let anslabel=new Label(Location=new System.Drawing.Point(120, 90), BorderStyle=BorderStyle.FixedSingle)
//make our buttons
let computebutton=new Button(Text="Compute", Location=new System.Drawing.Point(100, 130))
let exitbutton=new Button(Text="Exit", Location=new System.Drawing.Point(200, 130))
//add the controls into the form
annulform.Controls.Add(n1label)
annulform.Controls.Add(firsttextbox)
annulform.Controls.Add(n2label)
annulform.Controls.Add(secondtextbox)
annulform.Controls.Add(n3label)
annulform.Controls.Add(anslabel)
annulform.Controls.Add(computebutton)
annulform.Controls.Add(exitbutton)

//when the compute button is clicked
computebutton.Click.Add(fun ans ->
let areaoflargecircle=Convert.ToDouble(firsttextbox.Text)
let areaofsmallcircle=Convert.ToDouble(secondtextbox.Text)
let areaofannulus=areaoflargecircle-areaofsmallcircle

//display the area of annulus value in the anslabel
anslabel.Text<-Convert.ToString(areaofannulus))
 //when the exit button is clicked, close the form            
exitbutton.Click.Add(fun exit -> annulform.Close())  
Application.Run(annulform)