After my previous blog about the option of using Method Chaining (Using New ABAP stuff – Method Chaining and CL_SALV_TABLE) I thought it would be a good idea to write something about my experiences with new string options like String Templates, Chaining of strings, and built-in string functions. Just as with Method Chaining, using these string options allow for making ABAP code terser, which means that fewer statements are needed for the same functionality, without compromising readability of the code.
What’s it al about?
Several new options for the handling of characters strings were introduced to ABAP in WAS702:
- String Templates: the option to create a character string out of literal texts, expressions, and control characters.
- Chaining Operator: chain two character-like operands into one new character string.
- Character String Functions: built-in functions for searching, processing and comparing strings.
I will first explain these options and give a few examples. The last paragraph explains how the use of string templates, combined with built-in functions and the use of functional methods, limits the number of needed ABAP statements.
Note that the ABAP Keyword documentation contains several built-in examples, related to old and new ABAP features. These examples can be executed and debugged and its code can be analysed. Moreover, the program DEMO_EXPRESSIONS offers 45 examples of character string and byte string processing.
String Templates
The purpose of a string template is to create a new character string out of literal texts and embedded expressions. It largely replaces the use of the WRITE TO statement, which will be explained later on.
A string template is defined by using the | (pipe) symbol at the beginning and end of a template.
DATA: character_string TYPE string.
character_string = |This is a literal text.|.
This example has in fact exactly the same result as:
character_string = `This is a literal text.`.
The added value of a string template becomes clear when combining literal texts with embedded expressions and control characters. Embedded expressions are defined within a string template with curly brackets
{ expression }. Note that a space between bracket and expression is obligatory.
An expression can be a data object (variable), a functional method, a predefined function or a calculation expression. Some examples are:
character_string = |{ a_numeric_variable }|.
character_string = |This resulted in return code { sy-subrc }|.
character_string = |The length of text element 001 ({ text-001 }) is { strlen( text-001 ) }|.
Embedded expressions have a default output format, but also several formatting options, comparable to the format options of the WRITE statement. Some examples are:
DATA: amount_field TYPE vbap-netwr VALUE '1234567.123',
currency_field TYPE vbap-waerk.
character_string = |{ amount_field CURRENCY = currency_field NUMBER = USER }|.
character_string = |{ amount_field COUNTRY = 'GB ' }|.
Two limitations for which I haven’t found a solution yet are:
1) I could not find a formatting option for Conversion Exits. Consider the example below: the WRITE….TO… calls the conversion exit KONPD that converts an internal project number to an external project id. The string template inserts the internal project number into the string.
DATA: project_number TYPE proj-pspnr.
SELECT SINGLE pspnr FROM proj INTO project_number .
WRITE project_number TO character_string2.
character_string = |{ project_number }|.
2) The following option for text-elements is not supported in an embedded expression:
WRITE : 'This is a text'(001).
The only option to use a numbered text is in an embedded expression:
character_string = |{ text-001 }|.
However, using the Chaining Operator offers a simple solution for this as is demonstrated below.
Chaining Operator
The Chaining Operator && can be used to create one character string out of multiple other strings and string templates. The use of the chaining operator largely replaces the CONCATENATE statement.
In this example, a number text, a space, an existing character string and a new string template are concatenated into a new character string.
character_string = 'Text literal'(002) && ` ` && character_string && |{ amount_field NUMBER = USER }|.
Built-in functions
SAP has added several new built-in functions for searching, comparing, and processing character strings. A few of these functions already existed before release WAS702, like for example, CHARLEN( ) or STRLEN( ). Other statements like FIND, REPLACE or TRANSLATE can now be replaced by built-in functions Also new functions have been added.
Note that these built-in functions can be used as part of string templates or in operand positions. In the ABAP keyword documentation, the added value of these functions is described as followed:
The string functions enable many string processing tasks to be done in operand positions where previously separate statements and auxiliary variables were required.
A few examples of built-in functions are:
string_result = to_mixed( val = string_field sep = ` ` ).
string_result = reverse( string_field ).
distance_between_strings = distance( val1 = string_field val2 = string_result ).
The functions
to_mixed and
reverse speak for themselves. The function
distance is a similarity function that calculates the minimum number of steps needed to change one string into another string, the so called
Levenshtein distance. I’m still looking for an opportunity to use it in one of my customer assignments :wink:
Compacting ABAP code by using new string options
Imagine that you have to create a tab-delimited file from an internal table with a line type, consisting of character and numeric type fields. Furthermore, you want the date and amount fields to be converted into a specific output format in the file.
The definition of the internal table could look like this:
TYPES: BEGIN OF ty_struct,
change_date TYPE d,
amount TYPE bf_dmbtr,"numeric type
currency_key TYPE waers,
text_field TYPE string,
END OF ty_struct.
Let us focus on the creation of one tab-delimited file entry. Pre-WAS702, this would look like this:
DATA: date_as_a_string TYPE c LENGTH 10,
amount_as_a_string TYPE c LENGTH 20.
WRITE <input_line>-change_date TO date_as_a_string .
WRITE <input_line>-amount TO amount_as_a_string CURRENCY input_line>-currency_key.
CONCATENATE date_as_a_string
amount_as_a_string
<input_line>-currency_key
<input_line>-text_field INTO download_line
SEPARATED BY cl_abap_char_utilities=>horizontal_tab.
Note that you need two variables and two WRITE TO statements to convert the date and amount field to a suitable output format. Using the amount field, which is a numeric field, directly in the CONCATENATE statement will lead to a syntax error.
Using a string template, chaining operator and control characters, these 5 statements can be reduced to only one statement:
download_line =
|{ <input_line>-change_date DATE = USER }\t| &&
|{ <input_line>-amount NUMBER = USER CURRENCY = <input_line>-currency_key }\t| &&
|{ <input_line>-currency_key }\t{ <input_line>-text_field } |.
The tab delimiter is inserted by using the control character \t.
This is just one of many examples that I can think of. Just consider the following snippets of code and consider the number of intermediate steps your would need to implement this functionality without string templates.
* Include a built-in function
log_information = |Number of entries in download: { lines( download_file ) } |.
* Include a functional method call
log_information = |My IP address = { cl_gui_frontend_services=>get_ip_address( ) }|.
Conclusion
In my daily life as an ABAP programmer, I’m working on customer SAP systems with basis versions ranging from R/3 4.6C up to WAS731 based systems. Not being able to use new string options on several older customer systems can be quite frustrating after having used them on other systems. I once fell into the trap of writing a program using string templates and method chaining. I then tried to install this program on another ECC60 system, but this failed because this system was based on WAS701. I had to rewrite parts of the program: define new intermediate variables, call intermediate methods to get values, and use the WRITE TO statement to get the proper date and amount values in my download.
So, if you’re working on a WAS702vv-based system, I would advice you to start using new ABAP possibilities because they will improve your speed of development and make your programs better maintainable. For me, I just enjoy discovering and trying new options and share my experiences with other programmers.
