Visual F# 100 Examples: Example Number 1

Starting today, I will be sharing to you guys some learning examples that will aid you in learning windows forms application programming in Visual F#. Our target is to be able to share at least 100 examples. Let’s start with example number 1:

Problem: Make a windows form application that will ask the user’s mental age and chronological age and display his intelligence quotient (IQ).

Solution:
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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 iqform=new Form(Text="Compute IQ", Size=new System.Drawing.Size(300, 200),StartPosition=FormStartPosition.CenterScreen,AutoScaleMode=AutoScaleMode.Font)  
  11. //creates a label  
  12. let n1label=new Label(Text="Mental age:",Top=20,Left=5,AutoSize=true)  
  13. let firsttextbox=new TextBox(Location=new System.Drawing.Point(80, 20))  
  14. //creates another label and change its text to “Second number:”  
  15. let n2label=new Label(Text="Chronological age:", Location=new System.Drawing.Point(0,50),AutoSize=true)  
  16. let secondtextbox=new TextBox(Location=new System.Drawing.Point(100,50))  
  17. //creates another label and change its text to sum  
  18. let n3label=new Label(Text="IQ:", Location=new System.Drawing.Point(0, 90),AutoSize=true)  
  19. //creates a label that will display the result of the computation  
  20. let anslabel=new Label(Location=new System.Drawing.Point(80, 90), BorderStyle=BorderStyle.FixedSingle)  
  21. //make our buttons  
  22. let addbutton=new Button(Text="Compute", Location=new System.Drawing.Point(100, 130))  
  23. let exitbutton=new Button(Text="Exit", Location=new System.Drawing.Point(200, 130))  
  24. //add the controls into the form  
  25. iqform.Controls.Add(n1label)  
  26. iqform.Controls.Add(firsttextbox)  
  27. iqform.Controls.Add(n2label)  
  28. iqform.Controls.Add(secondtextbox)  
  29. iqform.Controls.Add(n3label)  
  30. iqform.Controls.Add(anslabel)  
  31. iqform.Controls.Add(addbutton)  
  32. iqform.Controls.Add(exitbutton)  
  33.   
  34. //when the compute button is clicked  
  35. addbutton.Click.Add(fun addfunction ->  
  36. let manum=Convert.ToDouble(firsttextbox.Text)  
  37. let canum=Convert.ToDouble(secondtextbox.Text)  
  38. let iq=Convert.ToDouble((manum/canum)*100.00)  
  39.   
  40. //display the iq value in the anslabel  
  41. anslabel.Text<-Convert.ToString(iq))  
  42.  //when the exit button is clicked, close the form              
  43. exitbutton.Click.Add(fun exit -> iqform.Close())    
  44. Application.Run(iqform)  
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Simplest input validation using Char.IsNumber and Char.IsLetter

The following example demonstrates how to validate a user input by using the Char.IsNumber and Char.IsLetter character manipulation functions:
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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 font  
  10. let ffont=new Font("Verdana", 9.75F,FontStyle.Regular, GraphicsUnit.Point)    
  11. let validateform = new Form(Text="Validate Inputs",AutoScaleDimensions=new System.Drawing.SizeF(60.0F, 13.0F),ClientSize=new System.Drawing.Size(300, 200),StartPosition=FormStartPosition.CenterScreen)  
  12. //creates our controls  
  13. let exitbutton=new Button(Text="Exit", Location=new System.Drawing.Point(190, 170))    
  14. let okbutton=new Button(Text="Ok", Location=new System.Drawing.Point(100, 170))   
  15. let label1=new Label(Text="Enter a name:",Location=new System.Drawing.Point(0, 10),AutoSize=true)  
  16. let nametxtbox=new TextBox(Location=new System.Drawing.Point(120,10),BorderStyle=BorderStyle.FixedSingle)  
  17. validateform.Font<-ffont  
  18. //adds the controls to our form  
  19. validateform.Controls.Add(exitbutton)  
  20. validateform.Controls.Add(okbutton)  
  21. validateform.Controls.Add(label1)  
  22. validateform.Controls.Add(nametxtbox)  
  23. //when the oK button is clicked  
  24. okbutton.Click.Add(fun ok->  
  25. //if the input begins with a letter then  
  26. if (Char.IsLetter(Convert.ToChar(nametxtbox.Text.Chars(0)))) then  
  27. //prompt that its a valid name  
  28. MessageBox.Show("The name you entered is valid ", "Validate Inputs",MessageBoxButtons.OK, MessageBoxIcon.Information)|>ignore  
  29. //if the input begins with a number then                           
  30. if (Char.IsNumber(Convert.ToChar(nametxtbox.Text.Chars(0)))) then  
  31. //prompt that its an invalid name  
  32. MessageBox.Show("You must enter a valid name", "Validate Inputs",MessageBoxButtons.OK, MessageBoxIcon.Information)|>ignore)  
  33. //when the exit button is clicked  
  34. exitbutton.Click.Add(fun exit->validateform.Close())  
  35. //executes our application  
  36. Application.Run(validateform)  
Click the run icon when done entering these codes in Visual F# code editor window. Try entering any number in the name text box and clicking the ok button. You should see an output similar to the following:

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