Introduction:
Welcome to my tutorial on how to create a Custom Command Line in Visual Basic using a form design.

Steps of Creation:
Step 1:
First we want to create a form with; listbox1 - to contain program output, textbox1 - to contain user input.

Step 2:
Next we want to access teh textbox1 keyPress event. We want to check if the pressed key is the Enter key, if it is we will run a custom function to process the input...

1. Private
   
   Sub
   
   TextBox1_KeyPress(sender As
   
   Object
   
   , e As
   
   KeyPressEventArgs) Handles TextBox1.KeyPress
   
2. If
   
   (e.KeyChar = ChrW(Keys.Enter)) Then
   
3. processCommand(TextBox1.Text)
   
4. End
   
   If
   
5. End
   
   Sub
   

Step 3:
So now we want to make our custom function which will run the input. First we create an 'ss' String variable which is set to the lower case version of the user input. We then create another variable as a Boolean which is set to False by default. This is because we set this to True whenever a comand is ran, this way we can tell if a command was successful or not and output accordingly.

We then want to create custom scripts for each command we want within our custom command line program. I have just done a couple; Output, to output a custom message in a messagebox. And open to open a file directory.

1. Private
   
   Function
   
   processCommand(ByVal
   
   s As
   
   String
   
   )
   
2. Dim
   
   ss As
   
   String
   
   = s.ToLower()
   
3. Dim
   
   successfulCommand As
   
   Boolean
   
   = False
   
4. If
   
   (ss.StartsWith("output "
   
   )) Then
   
5. MsgBox(s.Substring(7, s.Count() - 7))
   
6. successfulCommand = True
   
7. ElseIf
   
   (ss.StartsWith("open "
   
   )) Then
   
8. Diagnostics.Process.Start(ss.Substring(5, ss.Count() - 5))
   
9. successfulCommand = True
   
10. End
    
    If
    
11. If
    
    (successfulCommand) Then
    
12. addCommand(s)
    
13. Else
    
    : addCommand("Failed: "
    
    & s)
    
14. End
    
    If
    
15. End
    
    Function
    

Step 4:
Finally we want to create our last custom function which simply adds output to the listbox.

1. Private
   
   Function
   
   addCommand(ByVal
   
   s As
   
   String
   
   )
   
2. ListBox1.Items.Add(s)
   
3. End
   
   Function
   

Project Complete!
Below is the full source code and download to the project files.

1. Public
   
   Class Form1
   
2. Private
   
   Sub
   
   TextBox1_KeyPress(sender As
   
   Object
   
   , e As
   
   KeyPressEventArgs) Handles TextBox1.KeyPress
   
3. If
   
   (e.KeyChar = ChrW(Keys.Enter)) Then
   
4. processCommand(TextBox1.Text)
   
5. End
   
   If
   
6. End
   
   Sub
   
7. 
   
8. Private
   
   Function
   
   processCommand(ByVal
   
   s As
   
   String
   
   )
   
9. Dim
   
   ss As
   
   String
   
   = s.ToLower()
   
10. Dim
    
    successfulCommand As
    
    Boolean
    
    = False
    
11. If
    
    (ss.StartsWith("output "
    
    )) Then
    
12. MsgBox(s.Substring(7, s.Count() - 7))
    
13. successfulCommand = True
    
14. ElseIf
    
    (ss.StartsWith("open "
    
    )) Then
    
15. Diagnostics.Process.Start(ss.Substring(5, ss.Count() - 5))
    
16. successfulCommand = True
    
17. End
    
    If
    
18. If
    
    (successfulCommand) Then
    
19. addCommand(s)
    
20. Else
    
    : addCommand("Failed: "
    
    & s)
    
21. End
    
    If
    
22. End
    
    Function
    
23. 
    
24. Private
    
    Function
    
    addCommand(ByVal
    
    s As
    
    String
    
    )
    
25. ListBox1.Items.Add(s)
    
26. End
    
    Function
    
27. End
    
    Class
    

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