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 FILEATTR Gets MS-DOS File Handle to Get File Date/Time Stamp - Q38492
 
 When you open a file with the OPEN statement in a Basic program, the
 file number that you provide is not the MS-DOS file handle. Instead,
 the file number acts as a pointer into an internal table that BASIC
 uses to hold the file handles. You can use the FILEATTR function to
 obtain the actual MS-DOS file handle.
 
 The syntax for getting the file handle is as follows:
 
    FILEATTR(filenumber, 2)
 
 The program example listed below shows how to obtain the MS-DOS file
 handle of a file using the FILEATTR function. This program then uses
 the file handle in an MS-DOS Interrupt call to return the file's date
 and time stamp.
 
 More Information:
 
 The code example listed below invokes MS-DOS Interrupt 21h (33 decimal)
 with function 57h (87 decimal) to get a file's date and time stamp from
 the file's directory entry. This interrupt requires an MS-DOS file
 handle as an argument. Basic's FILEATTR function is used to retrieve
 the file handle before invoking the interrupt.
 
 Code Example
 ------------
 
 DEFINT A-Z
 ' To run this program in the environment, you must invoke the
 ' environment with the /L switch to load the default Quick library:
 '    VBDOS.EXE /L          for Visual Basic 1.0 for MS-DOS
 ' Use the following include file for Visual Basic 1.0 for MS-DOS:
 REM $INCLUDE: 'VBDOS.BI'
 
 DIM inregs AS RegType, outregs AS RegType
 ON ERROR GOTO ErrorHandler
 CLS
 INPUT "Enter filename:", filename$
 
 OPEN filename$ FOR INPUT AS #1
 filename$ = filename$ + CHR$(0)  ' ASCIIZ (Null on end).
 inregs.ax = &H5700
 inregs.bx = FILEATTR(1, 2)       ' Get DOS File Handle.
 CALL INTERRUPT(&H21, inregs, outregs)
 
 REM Date is returned in outregs.dx.
 REM   Day   : Bits 0-4
 REM   Month : Bits 5-8
 REM   Year  : Bits 9-15 (from 1980)
 Day = outregs.dx AND 31                ' Mask the upper bits.
 Month = (outregs.dx \2 ^ 5) AND 15    ' Shift L 5 & mask upper bits.
 Year = 1980 + (outregs.dx \2 ^ 9)     ' Shift left 9 & add 1980.
 PRINT "Month ="; Month; "  Day ="; Day; "  Year ="; Year
 
 REM Time is returned in outregs.cx
 REM   Seconds : Bits 0-4 (2 second increments)
 REM   Minutes : Bits 5-10
 REM   Hours   : Bits 11-15
 seconds = 2 * (outregs.cx AND 31) '  Mask the upper bits & mult. by 2.
 minutes = (outregs.cx \2 ^ 5) AND 63  ' Shift L 5 & mask upper bits.
 hours = outregs.cx     ' Shift left 11 - Be sure to shift in zeros!
 hours = hours \2
 hours = hours AND 32767
 hours = hours \2 ^ 10
 PRINT "Sec ="; seconds; "  Min ="; minutes; "  Hours ="; hours
 SHELL "dir " + filename$
 CLOSE #1
 END
 
 ErrorHandler:
         IF ERR = 53 THEN    ' File Not Found.
           PRINT "Incorrect path or File does not exist"
         ELSE
           PRINT ERR
         END IF
         END