b.santos/abap-cheat-sheets
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Update 07_String_Processing.md

Browse Source
This commit is contained in:
Dan
2023-01-09 16:50:14 +01:00
committed by GitHub
parent bcd4ba50f1
commit b513b97294
1 changed files with 86 additions and 101 deletions
Download Patch File Download Diff File Expand all files Collapse all files

167
07_String_Processing.md
View File

@@ -4,8 +4,8 @@
- [String Processing](#string-processing) - [String Processing](#string-processing)
- [Introduction](#introduction) - [Introduction](#introduction)
- [Variable Length and Fixed Length Character Strings](#variable-length-and-fixed-length-character-strings) - [Data Types for Character Strings](#data-types-for-character-strings)
- [Declaring Character-Like Data Types and Objects](#declaring-character-like-data-types-and-objects) - [Declaring Character-Like Data Objects](#declaring-character-like-data-objects)
- [Assigning Values](#assigning-values) - [Assigning Values](#assigning-values)
- [String Templates](#string-templates) - [String Templates](#string-templates)
- [Determining the Length of Strings](#determining-the-length-of-strings) - [Determining the Length of Strings](#determining-the-length-of-strings)
@@ -28,109 +28,92 @@
## Introduction ## Introduction
ABAP offers plenty of options for processing [character ABAP offers plenty of options for processing [character strings](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abencharacter_string_glosry.htm "Glossary Entry").
strings](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abencharacter_string_glosry.htm "Glossary Entry"). The options include ABAP statements (e. g. [`FIND`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapfind.htm)),
The options include ABAP statements (e. g. [character string expressions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_expression_glosry.htm "Glossary Entry")
[`FIND`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapfind.htm)), ([concatenations](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconcatenation_glosry.htm) and [string templates](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_template_glosry.htm "Glossary Entry"))
[character string and built-in [string functions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_function_glosry.htm "Glossary Entry")
expressions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_expression_glosry.htm "Glossary Entry") (e. g. [`strlen`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenlength_functions.htm)).
(e. g. [string
templates](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_template_glosry.htm "Glossary Entry"))
and built-in [string
functions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenstring_function_glosry.htm "Glossary Entry")
(e. g.
[`strlen`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenlength_functions.htm)).
> **💡 Note**<br> > **💡 Note**<br>
>- Expressions and string functions can help make your ABAP code more >- Compared to statements, expressions and string functions can help make your ABAP code more
concise and straightforward. For example, string operations can be concise and straightforward. For example, string operations can be
done directly in [operand done directly in [operand
position](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_position_glosry.htm "Glossary Entry") position](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_position_glosry.htm "Glossary Entry")
and, thus, you can avoid temporary variables. and, thus, you can avoid temporary variables.
>- In ABAP statements, modify operations on strings are frequently done >- In ABAP statements, modification operations on strings are frequently done in read/write positions, meaning that the source field and the target
on the source field which is the target field at the same time. fields of an operation are the same. When working with string functions, the source field is passed as an input parameter and the modified value is returned as a [return value](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenreturn_value_glosry.htm "Glossary Entry"), meaning that the function itself does not modify the source field. Of course, you can assign the function to the source field to achieve its modification.
String functions never modify the source field. Instead, the
modified string is provided as a [return
value](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenreturn_value_glosry.htm "Glossary Entry").
>- In most cases, string functions offer the same functionality as the >- In most cases, string functions offer the same functionality as the
corresponding ABAP statements. The return value of string functions corresponding ABAP statements or even more. The return value of string functions
that return character strings is always of type `string`. that return character strings is always of type `string`.
<p align="right">(<a href="#top">back to top</a>)</p> <p align="right">(<a href="#top">back to top</a>)</p>
### Variable Length and Fixed Length Character Strings ### Data Types for Character Strings
Built-in character-like types in ABAP are as follows: ABAP mainly offers the following built-in data types for data objects that contain character strings. They can be distinguished as follows:
| Type | Length | Value Range | Initial Value | | Type | Details | Length | Value Range | Initial Value |
|---|---|---|---| |---|---|---|---|---|
| `string` | Variable, i. e. the length of [data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendata_object_glosry.htm "Glossary Entry") of this type can change during the execution during the execution of ABAP programs (hence, they are also referred to as [dynamic data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendynamic_data_object_glosry.htm "Glossary Entry")); no standard length | Any characters | Empty string with length 0 | | `string` | For variable length character strings. [Data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendata_object_glosry.htm "Glossary Entry") of this type are [dynamic data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendynamic_data_object_glosry.htm "Glossary Entry"), i. e. the length of a variable can change during the execution of an ABAP program and thus it can contain character strings of different lengths. A data object of type `string` is called *text string* or, in short, just *string*. | No standard length; length is variable | Any [Unicode](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenunicode_glosry.htm) characters that can be encoded in ABAP language's code page [UCS-2](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenucs2_glosry.htm). The most common content are alphanumeric characters or special characters. | Empty string with length 0 |
| `c` | Data objects of this type contain a string of fixed length (between 1 and 262143 characters); standard length: 1 | Any characters | blank for every position | | `c` | For fixed length character strings. Data objects of this type are [static data objects](http://ldcialx.wdf.sap.corp:50018/sap/public/bc/abap/docu?sap-language=EN&object=abenstatic_data_object_glosry&version=X&sap-client=000), i. e. the length of a variable must be defined during its declaration and does not change during the execution of an ABAP program. Thus, it always contains character strings of the same length. A data object of type `c` is called *text field*.|Data objects of this type can contain a string of fixed length (between 1 and 262143 characters); standard length: 1 | Same as for `string` | A blank for each position |
| `n` | Same as for `c` | Any characters; valid values are only the digits 0 to 9.<br><br> Note that the restrictions for this type to only accept digits are not enforced, hence, fields may contain invalid data. The type is especially used for digits that are not meant for arithmetic calculations like zip codes or article numbers. | 0 for every position |
> **💡 Note**<br> Besides these main data types for character strings, there are some other fixed length data types with special meanings:
> [Byte-like data
types](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenbyte_like_data_typ_glosry.htm "Glossary Entry")
(`x`, `xstring`) and types that are specializations of
the type `c` (`n`, `d` referring to date and
`t` referring to time) are not covered in this cheat sheet.
> **⚡ Differences between variable length and fixed length strings**<br> - `n` for fixed length numerical character strings
>- **Initial value**: The initial value of variable length strings is an - Data objects of this type are technically almost the same as text fields. However, valid characters are only the digits 0 to 9. The validity is not checked when assigning values in a regular way but only for [lossless assignments](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenlossless_assignment_glosry.htm). Thus, such numeric text fields can contain invalid data, but should only be used for digits that are not meant for arithmetic calculations like zip codes or article numbers. The initial value is 0 for each position.
empty string with length 0. Fixed length strings have a standard - `d` and `t` for date and time fields
length of 1 character. - These data types have a predefiend length of 6 and 8. Data objects of these types are used for character representaions of dates and times in a predefined format. You can use them directly in date and time calculations. However, these fields can contain invalid values, too.
>- **Performance**: Data objects of both type `c` and
`string` are considered as [elementary data These data types are not covered further in this cheat sheet. The same is true for the [byte-like data types](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenbyte_like_data_typ_glosry.htm "Glossary Entry") `x` and `xstring` that are closely related to `c` and `string` but contain raw [byte strings](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenbyte_string_glosry.htm).
objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenelementary_data_object_glosry.htm "Glossary Entry").
However, data objects of type `string` are internally > **⚡ Differences between text strings (variable length) and text fields (fixed length)**<br>
managed as >- **Initial value**: The initial value of a text string is an
[references](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenreference_glosry.htm "Glossary Entry") empty string with length 0. A text field's initial value is represented by blanks for each position.
and are, thus, considered as >- **Internal representation**: Data objects of type `c` and `string` are both [elementary data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenelementary_data_object_glosry.htm "Glossary Entry").
[deep](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendeep_glosry.htm "Glossary Entry"). However, while text fields occupy a block of memory according to their length, text strings are so-called [deep](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendeep_glosry.htm "Glossary Entry") data objects. Internally, they are managed by a [reference](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenreference_glosry.htm "Glossary Entry") that points to the actual character. This fact has restricting consequences for using strings as components of structures but can also boost the performance of assignments because of the concept of [sharing](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensharing_glosry.htm "Glossary Entry") of deep data objects.
This fact enables the performance boosting concept of >- **Length**: Theoretically, a text string can use up to 2 GB (one character occupies 2 bytes).
[sharing](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensharing_glosry.htm "Glossary Entry") The maximum length of a text field is 262143 characters.
for data objects of this type when making value assignments. >- **Trailing blanks**: For text strings, trailing blanks are preserved in all operations. For text fields, it depends on the [operand
>- **Length**: Theoretically, a variable length string can use up to 2 GB. position](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_position_glosry.htm "Glossary Entry") whether trailing blanks are respected or not. In most operand positions, trailing blanks are truncated when working with text fields, even when using [text field literals](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abentext_field_literal_glosry.htm). For example, if a text field is assigned to a text string, the resulting target string never contains any trailing blanks. Note in this context the section *Condensing Strings*.
The maximum length of a fixed length string is 262143 characters. >- **Flexibility**: Text strings are more flexible than text fields
>- **Handling trailing blanks**: Usually, the [operand because you can easily shorten or extend them without
position](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_position_glosry.htm "Glossary Entry")
determines whether trailing blanks are respected or not. Fixed
length strings usually ignore trailing blanks; variable length
strings respect them. For example, if a fixed length string is
assigned to a variable length string, the target string does not
contain any trailing blanks. Note in this context the section
*Condensing Strings*.
>- **Flexibility**: Variable length strings are more flexible than fixed
length strings because you can easily shorten or extend them without
worrying that, for example, parts of the character string are worrying that, for example, parts of the character string are
truncated when processing. truncated when processing. On the other hand, when accessing substrings of a string, you must take care that the string is long enough, while for text fields you always know their length.
>- **Specifying values** for character strings in the ABAP source code
([literals](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenliteral_glosry.htm "Glossary Entry"))
with the types `c` and `string`: With quotes
(`'...'`), you create [text field
literals](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentext_field_literal_glosry.htm "Glossary Entry")
of type `c`, with backquotes (<code>\`...\`</code>), you create [text
string
literals](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentext_string_literal_glosry.htm "Glossary Entry")
of type `string`.
So, when to actually use what? Fixed length strings make sense when So, when to actually use what? Text fields make sense when
actually determining a maximum or mandatory length, e. g. a country code actually determining a maximum or mandatory length, e. g. a country code
that must consist of a maximum of two characters or input fields in that must consist of a maximum of two characters or input fields in
forms that should not exceed a certain length. If restricting a string forms that should not exceed a certain length. If restricting a string
is not relevant, variable length strings are a good choice. is not relevant, text strings are a good choice.
<p align="right">(<a href="#top">back to top</a>)</p> <p align="right">(<a href="#top">back to top</a>)</p>
## Declaring Character-Like Data Types and Objects ## Declaring Character-Like Data Objects
Character-like data types and objects are declared like other types and For working with character strings, you need character-like data objects, that are based on the above mentioned character-like types.
objects using
[`TYPES`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abaptypes.htm) The simplest way of producing text in an ABAP program are [character literals](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abencharacter_literal_glosry.htm).
and The following code snippet shows a global class implementing the interface `if_oo_adt_classrun`. Using the `write` method, you can display output in the ADT console. In the example, two [untyped literals](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenuntyped_literal_glosry.htm) without a dedicated name ([unnamed data object](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenunnamed_data_object_glosry.htm)) are included. In the case below, the data type of the character literals are defined by the delimiters.
[`DATA`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapdata.htm) Text string literals are enclosed in backquotes (<code>\`...\`</code>) and have the data type `string`. Text field literals are enclosed in single quotes (`'...'`) and have the data type `c`. The literals can be (but should not according to the [programming guidelines on literals (F1 docu for standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenliterals_guidl.htm)) used like constants of these types in [operand positions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_position_glosry.htm). They should be only used for start values when declaring [named data objects](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abennamed_data_object_glosry.htm).
statements. This cheat sheet focuses on the built-in types `c`
and especially on `string` in most examples. ```abap
CLASS zcl_some_test_class DEFINITION PUBLIC FINAL CREATE PUBLIC.
PUBLIC SECTION.
INTERFACES if_oo_adt_classrun.
ENDCLASS.
CLASS zcl_some_test_class IMPLEMENTATION.
METHOD if_oo_adt_classrun~main.
out->write( `I am a text string literal` ). "text string literal of type string
out->write( 'I am a text field literal' ). "text field literal of type c
ENDMETHOD.
ENDCLASS.
```
[Named](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abennamed_data_object_glosry.htm) character-like data types and objects can be declared like other types and objects using [`TYPES`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abaptypes.htm), [`DATA`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapdata.htm) [`CONSTANTS`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapconstants.htm) and by referring to a character-like data type.
Furthermore, character-like data objects can be declared inline with the operators `DATA` and, in newer ABAP releases, `FINAL` as shown further down.
Syntax examples: Syntax examples:
``` abap ``` abap
@@ -164,16 +147,12 @@ DATA char_len_one TYPE c.
## Assigning Values ## Assigning Values
When declaring character-like data objects, you can directly provide When declaring character-like data objects, you can directly provide
default values. For the assignment of values, you can, for example, use start values. For the assignment of values, you can, for example, use
the [assignment the [assignment operator](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenassignment_operator_glosry.htm "Glossary Entry")
operator](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenassignment_operator_glosry.htm "Glossary Entry") `=`.
`=`. To do both data object declaration and value assignment in As mentioned above, character-like data objects can be declared inline with the operators `DATA` or, in newer ABAP releases, `FINAL`. You can use the operators at many [write positions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenwrite_position_glosry.htm "Glossary Entry"). Compared to the `VALUE` addition of the declaration statements, inline declarations allow you to declare variables for results of expressions or in other positions where character strings are returned.
one go, you can make use of [inline In the case below, a variable specified in parentheses preceded by
declaration](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abendata_inline.htm) `DATA` (or `FINAL`) on the left side of the assignment operator automatically
that supports declarations in [write
positions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenwrite_position_glosry.htm "Glossary Entry").
In doing so, a variable specified in parentheses preceded by
`DATA` on the left side of the assignment operator automatically
derives a data type from the operand on the right. This helps make your derives a data type from the operand on the right. This helps make your
programs leaner. programs leaner.
@@ -187,6 +166,9 @@ DATA: flag TYPE c LENGTH 1 VALUE 'X',
DATA zip_code TYPE n LENGTH 5 VALUE '12345'. DATA zip_code TYPE n LENGTH 5 VALUE '12345'.
DATA isbn_number TYPE n LENGTH 13 VALUE '1234567890123'. DATA isbn_number TYPE n LENGTH 13 VALUE '1234567890123'.
"Constant; content cannot be changed at runtime
CONSTANTS pi TYPE p LENGTH 8 DECIMALS 14 VALUE '3.14159265358979'.
"More data object declarations "More data object declarations
DATA: char1  TYPE c LENGTH 5, DATA: char1  TYPE c LENGTH 5,
      html   TYPE string,       html   TYPE string,
@@ -209,6 +191,9 @@ DATA str4 TYPE string VALUE -1. "type i
DATA(char2) = 'abcd'. "Type c length 4 DATA(char2) = 'abcd'. "Type c length 4
DATA(str5)  = `efgh`. DATA(str5)  = `efgh`.
"In newer ABAP releases, you can use FINAL to create immutable variables.
FINAL(final_string)  = `zyx`.
"Since char2 is of type c length 4 (the length is also derived), "Since char2 is of type c length 4 (the length is also derived),
"characters are truncated in the following example assignment "characters are truncated in the following example assignment
char2 = 'ijklmnopq'. "ijkl char2 = 'ijklmnopq'. "ijkl