Code Snippet Series: Trimming Leading and Trailing Whitespace

This post is part of a series on code snippets. The complete list of posts in the series is available in the document Code Snippets: A Blog Series.

ABAP keyword CONDENSE is useful to remove leading and trailing space characters from a character string, however CONDENSE does not recognize other non-printing whitespace characters such as carriage returns, newlines and horizontal tabs.

Regular expressions give us a useful tool to recognize a wide variety of whitespace characters. The regular expression abbreviation [[:space:]], alternatively written as \s, represents the character set for all non-printing blank characters including space, carriage return, newline and horizontal tab.

The method below removes first trailing then leading whitespace characters from a changing parameter a_string of type string. This code may be used in any ABAP routine but is particularly useful for post-processing of user input in Web Dynpro UI elements such as a TextEdit.

METHOD trim_whitespace.
  DATA lv_strlen TYPE i.
  DATA lv_char TYPE string.
* Remove trailing whitespace from a_string
  DO.
      lv_strlen = strlen( a_string ) - 1.
      lv_char = a_string+lv_strlen(1).
      FIND REGEX '[[:space:]]' IN lv_char.
      CASE sy-subrc.
          WHEN 0.
              SHIFT a_string RIGHT DELETING TRAILING lv_char.
          WHEN OTHERS.
              EXIT.
      ENDCASE.
  ENDDO.
* Remove leading whitespace from a_string
  DO.
      lv_char = a_string+0(1).
      FIND REGEX '[[:space:]]' IN lv_char.
      CASE sy-subrc.
          WHEN 0.
              SHIFT a_string LEFT DELETING LEADING lv_char.
          WHEN OTHERS.
              EXIT.
      ENDCASE.
  ENDDO.
ENDMETHOD.