FileSize function

  DECLARATION:  FileSize(var F)

      PURPOSE:  Returns the current size of a file.

         UNIT:  System

  RESULT TYPE:  LongInt

      REMARKS:  Where F is a file variable, FileSize will
                return the number of components in F.
                If the file variable is of type byte, then it will
                return the size of that file in bytes.  If the file
                is empty, it will return 0.

                NOTE: With {$I-}, errors are returned through IOResult

 RESTRICTIONS:  Cannot be used on Text files.
                File must be open.

  DIFFERENCES:  The result type in v3.0 was an integer.

      EXAMPLE:  Var
                F        : File of Byte;
                FileName : String;

                Begin
                   Write('Enter File Name: ');
                   Readln(FileName);
                   Assign(F,FileName);
                   Reset(F);
                   Writeln('File size in bytes is: ',FileSize(F));
                   Close(F);
                 End.