Advanced 'FileExists' (determine if file exists) [RESOLVED]

[baja_yu]

Does anyone know a more advanced way of determining if a file (path) exists?

I am currently using

Dim FileExists as Boolean
 
FileExists = Not (Dir(txtPath.Text) = "")

This works ok for plain paths like C:\autoexec.bat or C:\Program Files\App\appfile.exe. But, the problem is if I have a complex path with switches and/or parameters like C:\Program Files\App\file.exe /o pic.jpg
Detecting "/" or "-" doesnt help as some parameters can be passed without those switches. And I cant use space (" ") as folders or files can contain them in their names.

Does anyone have an idea on this?

[Merri]

C:\Program Files\App\file.exe

should be

"C:\Program Files\App\file.exe"

Then you could just check for the first character to see if it is a quote, if it is, look for the next quote and there you are. If it isn't quote, look for a space character, if there is none then you can use the whole string.

Public Function FileExists(ByVal Filename As String) As Boolean
    Dim LeftChar As String * 1, A As Long
    Const QUOTE As String = ChrW$(34)
    LeftChar = Filename
    If LeftChar = QUOTE Then
        A = InStr(2, Filename, QUOTE, vbBinaryCompare)
        If A < 1 Then Exit Function
        Filename = Mid$(Filename, 2, A - 2)
    ElseIf InStr(Filename, " ") Then
        Filename = Left$(Filename, InStr(Filename, " ") - 1)
    End If
    FileExists = LenB(Dir$(Filename)) <> 0
End Function

[RobDog888]

This is what I think is the best method for determining if a
file exists or not. Just pass the filepath and name as a string.

Option Explicit
 
Private Const OF_EXIST = &H4000
Private Const OFS_MAXPATHNAME = 128
 
Private Type OFSTRUCT
    cBytes As Byte
    fFixedDisk As Byte
    nErrCode As Integer
    Reserved1 As Integer
    Reserved2 As Integer
    szPathName(OFS_MAXPATHNAME) As Byte
End Type
 
Private Declare Function OpenFile Lib "kernel32" (ByVal lpFileName As String, lpReOpenBuff As OFSTRUCT, ByVal wStyle As Long) As Long
 
Public Function FileExists(ByVal sFile As String) As Long
 
    Dim lRetVal As Long
    Dim OfSt As OFSTRUCT
    
    lRetVal = OpenFile(sFile, OfSt, OF_EXIST)
    If lRetVal = 1 Then
        FileExists = 1
    Else
        FileExists = 0
    End If
    
End Function
 
'Usage:
Private Sub Command1_Click()
    If FileExists("C:\DeleteMe\Test.txt") = 1 Then
        Msgbox "File Exists!"
    Else
        'MsgBox "File Not Found!"
    End If
End Sub

VB/Outlook Guru!

[Merri]

Oh, and another function that came to my mind is my QuoteSplit: it works real good for this kind of stuff, as you just need to call it and then take the first item it returns

Btw, RobDog, you could just have:

Public Function FileExists(ByVal sFile As String) As Boolean
    Dim lRetVal As Long
    Dim OfSt As OFSTRUCT
    FileExists = OpenFile(sFile, OfSt, OF_EXIST) = 1
End Function

[RobDog888]

Merri, I have sen that syntax used elsewhere. Could you explain
that syntax for me?

[Merri]

Lets split it into math:

'step one - functions called:
FileExists = OpenFile(sFile, OfSt, OF_EXIST) = 1
 
'step two - ready to process math operators:
FileExists = 1 = 1
 
'step three - ready to place the result to variable:
FileExists = True

I hope this is clear

[RobDog888]

So it is the evaluation of a mathmatical equation that will return a
true or false. Cool. Learned something new today and its only
10:00 am.

So its like this:

'step two - ready to process math operators:
FileExists = (1 = 1) '(1 = 1) = Return True.

Thanks Merri!

[baja_yu]

I am not at home right now so I couldnt test this. I will as soon as I get home.

Will this work if a path passed to it includes command line parameters. Like: "C:\Windows\System32\mspaint.exe /o c:\me.jpg"

(This may not be correct syntax for this app... its just an example)

[Merri]

No, that wouldn't work. Hmm... these are valid:

"C:\Program Files\Some.exe"
"C:\Program Files\Some.exe" /o /p
"C:\Program Files\Some.exe" C:\Somefile.txt
"C:\Program Files\Some.exe" "C:\Program Files\Some file.txt"
C:\Windows\Some.exe /o /p
C:\Windows\Some.exe "C:\Program Files\Some file.txt"

Valid means, these would work as a Windows' shortcut. Whenever there is a space in the path or filename, quotes must be used or you'll get an error, because anything space separated would be considered a parameter. The same works in the shortcuts as they do in programming (ie. when you try to Shell or ShellExecute something). This logic goes with the function I did, too

[baja_yu]

That is true, but how would you determine the main path in this case you menitoned:

C:\Windows\Some.exe /o /p

if it looked something like:

C:\Program Files\My App\app file.exe /o /p

when there are multiple (and you dont know how many) spaces in the path before parameters...

[Merri]

Well, there should be quotes in the first place. How are you getting them like that?

The only way to parse that kind of data, which wouldn't be 100% failure proof, would be to look for the last \ and then for a dot and then for a space.

[baja_yu]

This is an exact example:

C:\Program Files\FarStone\VirtualDrive\vdtask.exe /AutoRestore

It is from the HKLM\Software\Microsoft\Windows\CurrentVersion\Run

That idea is almost failproof except in case the extension has a space in it...

[Merri]

Extension can't have a space in it. If there is a space after a dot, it means the dot is part of a filename. Thus... there should be a lookup for a possible next dot.

Now that I think about it, the most failproof way would be to check for a space, if is a space, mark the location, then look the next character until it finds a dot. Then take characters to the last position a space was found.

'in a module
Public Function RemoveParams(ByVal Filename As String) As String
    Dim Buffer() As Byte
    Dim A As Long, B As Long
    Buffer = Filename
    A = (UBound(Buffer) Or 1) - 1
    Do While Buffer(A) = 46
        If Buffer(A) = vbKeySpace Then B = A
        A = A - 2
        If A < 0 Then RemoveParams = Buffer: Exit Function
    Loop
    ReDim Preserve Buffer(B - 1)
    RemoveParams = Buffer
End Function