Code Snippet Series: Trim 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.
Hi Amy King,
I really appreciate this blog. You helped me a lot … I was in trouble both with the statements
CONDENSE and with a combination of “DELETE LEFT LEADING space” and “DELETE RIGHT TRAILING space“.
Thanks a lot ?
I'm glad it was helpful Stefano, thank you!
I have liked to use CONDENSE, but also want to preserve repeating spaces inside the string
this method does that nicely.
Is there a simple way to preserve the leading spaces if required?
"SHIFT ... RIGHT DELETING TRAILING ..." removes trailing space at the end of a string.
"SHIFT ... LEFT DELETING LEADING ..." removes leading space at the beginning of a string.
To preserve leading spaces, avoid using the latter.
The caret ^ character in regular expressions indicates "the start of the string" and can help you to identify whether a string contains whitespace at its beginning:
Similarly, the dollar sign $ in regular expressions indicates "the end of the string" and can help you to identify whether a string contains whitespace at its end.
"To preserve leading spaces, avoid using the latter."
but this can introduce new leading spaces because the string has now been shifted right
" abc " => " abc"
all I can think of at the moment is to substitute leading whitespace with some other character, then shift right, shift left, then replace the original leading characters. which feels a bit messy