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| Prerequisites |
| Version 4.71 and later of Shlwapi.dll. |
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 Windows
Shlwapi.dll exposes a great number of path-oriented functions designed for use by the Windows shell. This series of pages shows how to
call these APIs, as well as the variety of results that each may return when passed one of several different file and path combinations. Each
demo wraps the API into a callable function, which either return True, False or a string, as appropriate. This page shows how to call the
PathFileExists API. The target must exist for this function.
Not all of the Shlwapi.dll path APIs are appropriate to all types of file and path data that can be passed. The illustrations for each method shows the typical return results when passed a variety of strings that represent:
The path functions themselves can be broken down into five basic categories (the names listed below are my wrapper function names on subsequent pages, and represent only a few of the 46 pages of path functions):
In order to show a complete demo using a combination of path and file strings representing typical application needs, each demo uses the same 26 strings as its test bed. This provides the opportunity to see exactly how each category of path information is handled by a specific call, as well as provide a single test bed upon which you can reuse the form while building a BAS module that contains just the functions you need. To create the environment to test these routines, I created a folder on C:\ called 'coolfocus', which contained a subfolder named javatools. In the javatools folder I placed a file named 'somefile.txt'. I also placed a copy of the somefile.txt in the c:\ root folder. I shared the coolfocus folder, and mapped a drive to it (drive m). A few of the path APIs (like the one detailed on this page) deal with actual paths, so requires that the file or path passed to the routine actually exist on the drive. But since the majority of the path functions deal with comparison and path syntax, they return the proper values whether the paths actually exist or not. This will become clearer in some of the other path demos. The form code below creates and labels the controls appropriate for this demo by just placing a single text and label on the form, setting both to create a control array. And although each of the path functions generally target a specific type of path statement (ie target URLs, or shares, etc), each demo reuses the same 26 file/path strings. |
| BAS Module Code |
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| Place the following code into the general declarations area of a bas module: |
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Option Explicit '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved. ' Some pages may also contain other copyrights by the author. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Distribution: You can freely use this code in your own ' applications, but you may not reproduce ' or publish this code on any web site, ' online service, or distribute as source ' on any media without express permission. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Private Declare Function PathFileExists Lib "shlwapi" _ Alias "PathFileExistsA" _ (ByVal pszPath As String) As Long Public Function FileExists(ByVal sPath As String) As Boolean 'Determines if a file exists. This function 'tests the validity of the file and path. It 'works only on the local file system or on a 'remote drive that has been mounted to a drive 'letter. ' 'It will return False for remote file paths 'that begin with the UNC names \\server 'or \\server\share. It will also return False 'if a mounted remote drive is out of service. ' 'Requires Version 4.71 and later of Shlwapi.dll FileExists = PathFileExists(sPath) = 1 End Function |
| Form Code |
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| To the form, add the following code: |
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Option Explicit
Private Sub Form_Load()
Dim cnt As Long
For cnt = 0 To 25
If cnt > 0 Then
Load Label1(cnt)
Load Text1(cnt)
End If
With Text1(cnt)
.Left = 300
.Top = 210 + (300 * cnt)
.Width = 700
.Text = "text1 " & CStr(cnt)
.Visible = True
End With
With Label1(cnt)
.Left = 1200
.Top = 250 + (300 * cnt)
.Caption = "label1 " & CStr(cnt)
.Visible = True
End With
Next
With Command1
.Left = 300
.Top = Text1(25).Top + (Text1(25).Height * 1.5)
.Caption = "FileExists"
End With
'display the strings that will be used in the call
'file only
Label1(0).Caption = "somefile.txt"
'absolute paths
Label1(1).Caption = "c:\"
Label1(2).Caption = "c:\somefile.txt"
Label1(3).Caption = "c:\javatools\"
Label1(4).Caption = "c:\javatools\somefile.txt"
'relative paths
Label1(5).Caption = "..\..\"
Label1(6).Caption = "..\..\somefile.txt"
Label1(7).Caption = "..\..\javatools\"
Label1(8).Caption = "..\..\javatools\somefile.txt"
'mapped drive
Label1(9).Caption = "m:\"
Label1(10).Caption = "m:\somefile.txt"
Label1(11).Caption = "m:\coolfocus\"
Label1(12).Caption = "m:\coolfocus\somefile.txt"
'UNC
Label1(13).Caption = "\\workstation"
Label1(14).Caption = "\\workstation\somefile.txt"
Label1(15).Caption = "\\workstation\javatools"
Label1(16).Caption = "\\workstation\javatools\somefile.txt"
'IP address
Label1(17).Caption = "\\192.168.1.100"
Label1(18).Caption = "\\192.168.1.100\somefile.txt"
Label1(19).Caption = "\\192.168.1.100\d$"
Label1(20).Caption = "\\192.168.1.100\d$\javatools\"
Label1(21).Caption = "\\192.168.1.100\d$\javatools\somefile.txt"
'URL
Label1(22).Caption = "ms.htm"
Label1(23).Caption = "www.microsoft.com"
Label1(24).Caption = "http://www.microsoft.com"
Label1(25).Caption = "http://www.microsoft.com/ms.htm"
End Sub
Private Sub Command1_Click()
'Parses a path to determine if it
'is a directory root. The path does
'not have to exist.
'as filename alone
Text1(0).Text = FileExists("somefile.txt")
'via absolute path
Text1(1).Text = FileExists("c:\")
Text1(2).Text = FileExists("c:\somefile.txt")
Text1(3).Text = FileExists("c:\javatools\")
Text1(4).Text = FileExists("c:\javatools\somefile.txt")
'via relative path
Text1(5).Text = FileExists("..\..\")
Text1(6).Text = FileExists("..\..\somefile.txt")
Text1(7).Text = FileExists("..\..\javatools\")
Text1(8).Text = FileExists("..\..\javatools\somefile.txt")
'via mapped drive
Text1(9).Text = FileExists("m:\")
Text1(10).Text = FileExists("m:\somefile.txt")
Text1(11).Text = FileExists("m:\coolfocus\")
Text1(12).Text = FileExists("m:\coolfocus\somefile.txt")
'via UNC
Text1(13).Text = FileExists("\\workstation")
Text1(14).Text = FileExists("\\workstation\somefile.txt")
Text1(15).Text = FileExists("\\workstation\javatools")
Text1(16).Text = FileExists("\\workstation\javatools\somefile.txt")
'via IP address
Text1(17).Text = FileExists("\\192.168.1.100")
Text1(18).Text = FileExists("\\192.168.1.100\somefile.txt")
Text1(19).Text = FileExists("\\192.168.1.100\d$")
Text1(20).Text = FileExists("\\192.168.1.100\d$\javatools")
Text1(21).Text = FileExists("\\192.168.1.100\d$\javatools\somefile.txt")
'via URL
Text1(22).Text = FileExists("ms.htm")
Text1(23).Text = FileExists("www.microsoft.com")
Text1(24).Text = FileExists("http://www.microsoft.com")
Text1(25).Text = FileExists("http://www.microsoft.com/ms.htm")
End Sub |
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Copyright ©1996-2011 VBnet and Randy Birch. All Rights Reserved. |
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