* VB-CODE (3)
Tip 73: Creating Nested Directories

May 1, 1995

You can use the Visual Basic® MkDir statement to create a new
directory on any floppy or hard disk. This article explains how you
can use this statement to create nested subdirectories, even if part
of the path already exists.

The MkDir Statement
When developing an application in Visual Basic®, you may need to allow
the user to store a data file in a specific directory on disk. The
dirctory can be created with Visual Basic's MkDir statement. The
syntax for this statement is:

MkDir "C:\"
where JUNK is the name of the directory you want to create and C:\ is
the drive you want to create it on. If you want to create a nested
subdirectory, for example C:\JUNK\TEST, you must first create the
JUNK directory and then create the TEST directory. However, if the
JUNK directory already exists, the MkDir statement will interrupt your
application with a "Path/File Access Error" displayed in a message
To prevent this error message from appearing when your application is
creating directories, you can use the On Error and Resume Next
statements. These two statements allow you to trap this access error
and force your Visual Basic program to continue executing as if the
error had not actually occurred.

The example program below creates a directory that is three levels
deep, called "\JUNK\TEST\TEST". The first time the MkDir statement is
executed, it creates the JUNK directory. The second and third times
MkDir is executed, however, it produces Error 76. The Resume Next
statement tells our program to ignore this error each time it is
encountered until we have successfully created the entire directory

Example Program
This program shows how to create nested directories even if one of
the directories in the path already exists.

 1. Create a new project in Visual Basic. Form1 is created by default.
 2. Add a Command Button control to Form1. Command1 is created by
    default. Set its Caption property to "Create Directory".
 3. Add the following code to the Click event for Command1:

Sub Command1_Click()
    CreateNewDirectory "C:\junk3\test\test"
    MsgBox "Directory was created", 16, "Dir Demo"
End Sub

 4. Create a new function called CreateNewDirectory. Add the following
    code to this function:

Sub CreateNewDirectory(DirName As String)
    Dim NewLen As Integer
    Dim DirLen As Integer
    Dim MaxLen As Integer

    NewLen = 4
    MaxLen = Len(DirName)        

    If Right$(DirName, 1) <> "\" Then
        DirName = DirName + "\"
        MaxLen = MaxLen + 1
    End If
    On Error GoTo DirError

    DirLen = InStr(NewLen, DirName, "\")
    MkDir Left$(DirName, DirLen - 1)
    NewLen = DirLen + 1
    If NewLen >= MaxLen Then
        Exit Sub
    End If
    GoTo MakeNext
    Resume Next
End Sub

Run the program by pressing the F5 function key. When you click the
"Create Directory" command button, the program creates a directory
called "JUNK\TEST\TEST" on drive C. Change the path in the Click event
for Command1 to "C:\JUNK\TEST\TEST2" and run the program a second
time. It will create a second subdirectory called TEST2 under
C:\JUNK\TEST. Notice that Error 76 is ignored by the program. This
error is generated by MkDir when it attempts to create a directory
(in this case, C:\JUNK\TEST) that already exists.