code:

---

;FUNCTION         OpenFile()
;
;AUTHOR           Howard A. Bullock (hbullock@tycoelectronics.com)
;
;ACTION           Opens file based on specified parameters. Supports overwriting a file.
;
;SYNTAX           OpenFile(FileName, R|W, [0|1], [0|1])
;
;PARAMETERS       $FileName (Required) -  String value
;                 $ReadWrite (Required) -  String value
;                 $Create (Optional) Default(0) Do not create a new file. (1 or 0)
;                 $OverWrite (Optional) - Default(0) Append (1 or 0)
;
;
;REMARKS          This function attempts to open the specified file. @error is set on exit.
;                 The UDF will search for the first available file number.
;
;RETURNS          File handle (integer 1-10) if successful; nothing if error
;
;DEPENDENCIES     None
;
;EXAMPLES         $FH = OpenFile("junk.txt", "W") ;Open file for write; do not create the file; append
;                 if @error = 0
;                    Writeline($FH, "Some text")
;                 endif
;
;                 $FH2 = OpenFile("junk2.txt", "W", 1, 1) ;Open file for write; create the file; delete old file
;                 if @error = 0
;                    Writeline($FH2, "Some text")
;                 endif;
;
Function OpenFile($FileName, $ReadWrite, optional $Create, optional $Overwrite)
	Dim $FileName, $ReadWrite, $Create, $Overwrite
	Dim $FH, $RC, $Mode

	; Validate input parameters
	if VarType($Create) = 0
		$Create = 0
	endif
	if VarType($Overwrite) = 0
		$Overwrite = 0
	endif
   if not (VarType($FileName) = 8 and
   		 ($ReadWrite = "R" or $ReadWrite = "W") and
   		 ($Create = 0 or $Create = 1) and
   		 ($Overwrite = 0 or $Overwrite = 1) )
   	;WriteLog($LogFile, "OpenFile: Error in parameters (" + $FileName + ", " + $ReadWrite + ", " + $Create + ", " + $OverWrite + ")")
   	exit 1
   endif
   if $Create < $OverWrite
   	;WriteLog($LogFile, "OpenFile: Error in parameters ("You must specify Create=1 when OverWrite=1")
   	exit 1
   endif

	; Build Mode value
	if $Create = 0
		$Mode = 0
	else
		$Mode = 1
	endif
	if $ReadWrite = "R"
		$Mode = $Mode + 2
	else
		$Mode = $Mode + 4
	endif

	;Handle OverWrite option
	if $OverWrite = 1
		if exist ($Filename)
			del $Filename
		endif
	endif

	; Open file
   $FH=1
   $RC=Open ($FH, $FileName, $Mode)
   ? "@error @serror"
	if $RC <> 0
		select
			case $RC=2
				;WriteLog("open($FileNum, $FileName, $Mode) Error: $RC (Cannot find the file specified)")
				exit $RC
			case $RC=-3
			   while $RC = -3 and $FH < 11
			      $RC=Open ($FH, $FileName, $Mode)
			      if $RC = -3
			      	$FH=$FH +1
			      endif
			   Loop
			   if $RC = -3
			   	;WriteLog("open($FileNum, $FileName, $Mode) Error: $RC (All file numbers are in use.)")
			   	exit $RC
			   endif
			case $RC=-2
				;WriteLog("open($FileNum, $FileName, $Mode) Error: $RC (Invalid file number specified)")
				exit $RC
			case $RC=-1
				;WriteLog("open($FileNum, $FileName, $Mode) Error: $RC (File number already in use)")
				exit $RC
			case 1
				;WriteLog("open($FileNum, $FileName, $Mode) Error: $RC (System error)")
				exit $RC
		endselect
	endif
	;WriteLog("Success: Open($FileNum, $FileName, $ReadWrite, $OverWrite) returned file handle: ")
	$OpenFile = $FH
	exit 0
Endfunction

  

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