Select File name using routine

Question

I am trying to write a routine in the info package for flat file extractionwhich will select the flat file automatically according to sy-datum ( the flat file is saved with system date). Here is my example code. Please help me in writing a correct code.
program filename_routine.
Global code
$$ begin of global - insert your declaration only below this line  -
TABLES:
DATA: str1(60) TYPE c,
      str2(10) TYPE c,
      str3(10) TYPE c.
     str4(100) type c.
str1 = 'C:\Documents and Settings\Yadavalli\Desktop'.
str2 = 'Sy-datum'.
str3 = 'csv'.
$$ end of global - insert your declaration only before this line   -
form compute_flat_file_filename
  changing p_filename type RSFILENM
           p_subrc like sy-subrc.
$$ begin of routine - insert your code only below this line        -
         concatenate str1 str2 str3 into str4.
  p_filename =
CONCATENATE str1 '\' str2 '.' str3 INTO str4.
  p_subrc = 0.
$$ end of routine - insert your code only before this line         -
endform.
Regards
Naga

Answer 1

I thought of using below Function Module but it is not loading the data. It is showing red. Please let me know whether i have mentioned logical_filename correctly.
$$ begin of routine - insert your code only below this line        -
CALL FUNCTION 'FILE_GET_NAME'
  EXPORTING
  CLIENT                        = SY-MANDT
    logical_filename              = 'C:\'
  OPERATING_SYSTEM              = SY-OPSYS
  PARAMETER_1                   = ' '
  PARAMETER_2                   = ' '
  PARAMETER_3                   = ' '
  USE_PRESENTATION_SERVER       = ' '
  WITH_FILE_EXTENSION           = ' '
  USE_BUFFER                    = ' '
  ELEMINATE_BLANKS              = 'X'
IMPORTING
  EMERGENCY_FLAG                =
   FILE_FORMAT                   =  'csv'
   FILE_NAME                     =  sy-datum
EXCEPTIONS
  FILE_NOT_FOUND                = 1
  OTHERS                        = 2
IF sy-subrc <> 0.
MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
        WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
Regards
Naga