Visual Basic Library

This page was last updated on Saturday, November 24, 2001

Public Function boolChar(intFile As Integer, strText As String, locStart) As Boolean
' Procedure :   boolChar
' Description:  Test if character of a file are present.
' Copyright:    Chris Greaves Inc.
' Inputs:       File handle, character string, start position in file.
' Returns:      TRUE if match is made.
' Assumes:      None.
' Side Effects: None.
' Tested:       By the calls shown below.

' Here is a function that tests specific characters of a file.
' Since it is an internal function it can assume that the given file is
'       at least long enough to hold the characters.
' I specify a file handle (so we know that the file exists and is open),
'       a string of characters to be sought, and a starting location.
' The starting location is zero-origin;
'       the first character is at seek position "0" in the file.
' The starting location can be expressed either as a decimal numeric value
'       or as a character string.
'       If the latter, I assume it is a hexadecimal location.
'       This means that if I am unscrambling a file using a hex portrayal
'       like Vernon Buerg's List.COM I can offer as a direct parameter
'       the displayed hexadecimal location in the file.

' The little testbed below should get you started; it determines if a file is a WordPerfect file.

    Dim lngStart As Long
    If IsNumeric(locStart) Then
        lngStart = locStart
    Else
        If VarType(locStart) = vbString Then
            lngStart = lngHexToLong(locStart)
        Else
            MsgBox "boolChar wrong type " & locStart
        End If
    End If
    Dim intLength As Integer
    intLength = Len(strText)
    Dim strChars As String
    Seek intFile, lngStart + 1
    strChars = Input(intLength, intFile)
    boolChar = (strChars = strText)
'Sub TESTboolChar()
'Dim intFile As Integer
'intFile = FreeFile
'Open "d:\greaves\training\wordpr~1\wp51\Maths.w51" For Binary As intFile
'MsgBox boolChar(intFile, "WPC", 1) ' true
'MsgBox boolChar(intFile, "WPC", "01") ' true
'MsgBox boolChar(intFile, "WPC", "02") ' false
'Close intFile
'End Sub
End Function