* VB-CODE (1)
Tip 153: Searching PATH for Specific Files

September 5, 1995

Abstract
The MS-DOS? PATH statement tells the operating system to look for files in
specific directories on your disk. This article explains how to find out
whether a specific file exists in one of the PATH directories.

Searching for Files
When you write a program in Microsoft? Visual Basic?, you may need to
determine if a specific file exists on a disk drive. At installation time,
many software packages modify the MS-DOS? PATH statement in the
AUOTOEXEC.BAT file by adding a new directory to the existing PATH
directories. This allows an application to find its own system or data
files that it requires to run successfully. You can add a search routine
to your program to search these directories for an individual file.

The first step is to retrieve the entire path for the specified disk
drive. The Visual Basic CurDir$ function returns the current disk drive's
path.
Next, you need to call two Microsoft Windows? application programming
interface (API) functions, GetWindowsDirectory and GetSystemDirectory. The
GetWindowsDirectory function retrieves the path of the Windows directory.
Windows stores its initialization files, help files, application files,
and other files in this directory. The GetSystemDiectory function
retrieves the path of the Windows system directory. Windows stores
library, font, drive, and other system files in this directory.

In the example program below, you use all three functions mentioned above
to build a string (PathStr) that contains the directory names. The
IsFileInPath function simply uses the InStr function to extract each
individual directory name from PathStr. Then you use the Dir$ function
to determine whether the target file exists in that directory.

Example Program
This program shows how to determine whether a specific file exists in one
of the directories in the PATH statement.

 1. Create a new project in Visual Basic. Form1 is created by default.
 2. Add the following Declare statements to the General Declarations
    section of Form1 (note that each Declare statement must be typed
    as a single line of code):

Private Declare Function GetSystemDirectory Lib "kernel32" Alias
   "GetSystemDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long)
   As Long
Private Declare Function GetWindowsDirectory Lib "kernel32" Alias
   "GetWindowsDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long)
   As Long

 3. Add a Text Box control to Form1. Text1 is created by default.
 4. Add a Command Button control to Form1. Command1 is created by default.
 5. Add the following code to the Click event for Command1:

Private Sub Command1_Click()
    Dim DirStr As String
    Dim FileToFind As String
    Dim Flag As Integer

    FileToFind = Text1.Text
    Flag = IsFileInPath(FileToFind, DirStr)
    If Flag Then
        MsgBox "File Exists in: " & DirStr
    Else
        MsgBox "File does not exist in PATH"
    End If
End Sub

 6. Create a new function called BuildSearchPath. Add the following code
    to this function:

Sub BuildSearchPath(PathStr As String)
    Dim RetVal As Integer
    Dim Buffer As String * 128

    PathStr = CurDir$
    RetVal = GetWindowsDirectory(Buffer, 128)
    PathStr = PathStr & ";" & Mid$(Buffer, 1, RetVal)
    Buffer = Space(128)
    RetVal = GetSystemDirectory(Buffer, 128)
    PathStr = PathStr & ";" & Mid$(Buffer, 1, RetVal)
    PathStr = PathStr & ";" & App.Path
    PathStr = PathStr & ";" & Environ$("PATH")
End Sub

 7. Create a new function called IsFileInPath. Add the following code to
    this function:

Function IsFileInPath(TheFile As String, DirName As String) As Integer
    Dim Separator As Integer
    Dim SearchStr As String
    Dim Results As String

    Call BuildSearchPath(SearchStr)

    While Len(SearchStr) <> 0
        Separator = InStr(SearchStr, ";")
        If Separator <> 0 Then
            DirName = Mid$(SearchStr, 1, Separator - 1)
            SearchStr = Mid$(SearchStr, Separator + 1)
        Else
            DirName = SearchStr
            SearchStr = ""
        End If

        Results = Dir$(DirName & "\" & TheFile)
        If Results <> "" Then
            IsFileInPath = True
            Exit Function
        End If
    Wend
    IsFileInPath = False
End Function

Run the example program by pressing F5. Type the name of a file that you
want to find in the Text Box control. Click the command button. A message
box will be displayed, telling you whether the file was found in one of
the PATH directories.

Additional References
"GetSystemDirectory." (Development Library, Product Documentation, SDKs,
   Win32 SDK, Win32 Programmer's Reference, Reference, Functions,
   GetQueueStatus to GetTextCharacterExtra)
"GetWindowsDirectory." (Development Library, Product Documentation, SDKs,
   Win32 SDK, Win32 Programmer's Reference, Reference, Functions,
   GetTextCharsetInfo to GetWinFlags)
"CurDir Function." (Development Library, Product Documentation, Languages,
   Visual Basic 4.0 Professional and Enterprise Editions,
   Language Reference, AZ Reference)