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

Update

Browse Source
This commit is contained in:
danrega
2024-05-02 16:52:38 +02:00
parent f0f1f76952
commit d40807c68d
2 changed files with 170 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files

220
13_Program_Flow_Logic.md
View File

@@ -243,26 +243,30 @@ ENDIF.
```abap
"IF statement with multiple included ELSEIF statements
IF log_exp1.
... "statement_block1
ELSEIF log_exp2.
... "statement_block2
ELSEIF log_exp3.
... "statement_block3
... "further ELSEIF statements
DATA(abap) = `ABAP`.
FIND `AB` IN abap.
IF sy-subrc = 0.
"found
...
ELSE.
... "statement_blockn
"not found
...
ENDIF.
"IF statement with multiple included ELSEIF statements
DATA(current_utc_time) = cl_abap_context_info=>get_system_time( ).
DATA greetings TYPE string.
IF current_utc_time BETWEEN '050000' AND '115959'.
greetings = |Good morning, it's { current_utc_time TIME = ISO }.|.
ELSEIF current_utc_time BETWEEN '120000' AND '175959'.
greetings = |Good afternoon, it's { current_utc_time TIME = ISO }.|.
ELSEIF current_utc_time BETWEEN '180000' AND '215959'.
greetings = |Good evening, it's { current_utc_time TIME = ISO }.|.
ELSE.
greetings = |Good night, it's { current_utc_time TIME = ISO }.|.
ENDIF.
```
@@ -304,12 +308,16 @@ ENDIF.
- Such conditional expressions have a result that is dependent on the logical expressions.
- The result's data type is specified after `COND` right before the first parenthesis. It can also be the `#` character as a symbol for the operand type if the type can be derived from the context. See the ABAP Keyword Documentation and the cheat sheet on constructor expressions for more information.
- All operands specified after `THEN` must be convertible to the result's data type.
- See also the [Constructor Expressions](05_Constructor_Expressions.md) cheat sheet for more information and examples.
```abap
DATA greetings_cond TYPE string.
DATA(current_utc_time_cond) = cl_abap_context_info=>get_system_time( ).
greetings_cond = COND #( WHEN current_utc_time_cond BETWEEN '050000' AND '115959' THEN |Good morning, it's { current_utc_time_cond TIME = ISO }.|
WHEN current_utc_time_cond BETWEEN '120000' AND '175959' THEN |Good afternoon, it's { current_utc_time_cond TIME = ISO }.|
WHEN current_utc_time_cond BETWEEN '180000' AND '215959' THEN |Good evening, it's { current_utc_time_cond TIME = ISO }.|
ELSE |Good night, it's { current_utc_time_cond TIME = ISO }.| ).
```abap
... COND type( WHEN log_exp1 THEN result1
WHEN log_exp2 THEN result2
...
ELSE resultn ) ...
```
<p align="right"><a href="#top">⬆️ back to top</a></p>
@@ -325,29 +333,49 @@ ENDIF.
```abap
CASE operand.
WHEN op1.
... "statement_block
WHEN op2.
... "statement_block
WHEN op3 OR op4.
... "statement_block
"Getting a random number
DATA(random_num) = cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
min = 1
max = 5 )->get_next( ).
DATA num TYPE string.
CASE random_num.
WHEN 1.
num = `The number is 1.`.
WHEN 2.
num = `The number is 2.`.
WHEN 3 OR 4.
num = `The number is either 3 or 4.`.
WHEN OTHERS.
... "statement_block
num = `The number is not between 1 and 4.`.
ENDCASE.
```
Special control structure introduced by [`CASE TYPE OF`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapcase_type.htm): Checks the type of object reference variables.
Special control structure introduced by [`CASE TYPE OF`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapcase_type.htm): Checks the type of object reference variables. An object reference variable with the static type of a class or an interface must be specified after `CASE TYPE OF`.
```abap
"oref must be an object reference variable with the static type of a class or an interface.
CASE TYPE OF oref.
WHEN TYPE some_class.
... "statement_block
WHEN TYPE some_intf.
... "statement_block
"The example shows the retrieval of type information at runtime (RTTI).
"For more information on RTTI, refer to the Dynamic Programming cheat
"sheet. The result of the method call is a type description object
"that points to one of the classes specified.
DATA stringtab TYPE TABLE OF string WITH EMPTY KEY.
DATA(type_description) = cl_abap_typedescr=>describe_by_data( stringtab ).
CASE TYPE OF type_description.
WHEN TYPE cl_abap_elemdescr.
...
WHEN TYPE cl_abap_enumdescr.
...
WHEN TYPE cl_abap_refdescr.
...
WHEN TYPE cl_abap_structdescr.
...
WHEN TYPE cl_abap_tabledescr.
"This is the class the type description object points to for
"the example data object.
...
WHEN OTHERS.
... "statement_block
...
ENDCASE.
```
@@ -355,15 +383,19 @@ ENDCASE.
#### Excursion: `SWITCH` Operator
The conditional operator [`SWITCH`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconditional_expression_switch.htm) can also be used to make case distinctions in operand positions. As mentioned above for `COND`, a result is constructed. The same criteria apply for `SWITCH` as for `COND` regarding the type. See the ABAP Keyword Documentation and the cheat sheet on constructor expressions for more information.
The conditional operator [`SWITCH`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconditional_expression_switch.htm) can also be used to make case distinctions in operand positions. As mentioned above for `COND`, a result is constructed. The same criteria apply for `SWITCH` as for `COND` regarding the type. See the ABAP Keyword Documentation and the cheat sheet on constructor expressions for more information. See also the [Constructor Expressions](05_Constructor_Expressions.md) cheat sheet for more information and examples.
```abap
... SWITCH type( operand
WHEN const1 THEN result1
WHEN const2 THEN result2
...
ELSE resultn ) ...
DATA(random_num_switch) = cl_abap_random_int=>create( seed = cl_abap_random=>seed( )
min = 1
max = 5 )->get_next( ).
DATA(num_switch) = SWITCH #( random_num_switch
WHEN 1 THEN `The number is 1.`
WHEN 2 THEN `The number is 2.`
WHEN 3 OR 4 THEN `The number is either 3 or 4.`
ELSE `The number is not between 1 and 4.` ).
```
<p align="right"><a href="#top">⬆️ back to top</a></p>
@@ -376,17 +408,23 @@ The conditional operator [`SWITCH`](https://help.sap.com/doc/abapdocu_cp_index_h
- The loop is exited when a statement to terminate the loop is reached (`EXIT`, see further down). Otherwise, it is executed endlessly.
```abap
DATA str_a TYPE string.
DO.
... "statement_block
"To be terminated with an EXIT statement.
str_a &&= sy-index.
IF sy-index = 5.
EXIT.
ENDIF.
ENDDO.
"str_a: 12345
```
- To restrict the loop passes, you can use the `TIMES` addition and specify the maximum number of loop passes.
```abap
DO 5 TIMES.
... "statement_block
DATA str_b TYPE string.
DO 9 TIMES.
str_b &&= sy-index.
ENDDO.
"str_b: 123456789
```
- The value of the system field `sy-index` within the statement block contains the number of previous loop passes including the current pass.
@@ -402,6 +440,54 @@ The following ABAP keywords are available for interrupting and exiting loops:
| [`CHECK`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapcheck_loop.htm) | `CHECK log_exp.` | Conditional termination. If the logical expression `log_exp` is false, the current loop pass is terminated immediately and the program flow is continued with the next loop pass. |
| [`EXIT`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapexit_loop.htm) | `EXIT.` | The loop is terminated completely. The program flow resumes after the closing statement of the loop. |
```abap
"------------ CONTINUE ------------
DATA str_c TYPE string.
DO 15 TIMES.
"Continue with the next loop pass if the number is even
"Terminating the loop pass and continuing with the next loop pass if the condition specified
"with the IF statement is true (if the number is even)
IF sy-index MOD 2 = 0.
CONTINUE.
ELSE.
str_c = |{ str_c }{ COND #( WHEN str_c IS NOT INITIAL THEN `, ` ) }{ sy-index }|.
ENDIF.
ENDDO.
"str_c: 1, 3, 5, 7, 9, 11, 13, 15
"------------ CHECK ------------
DATA str_d TYPE string.
DO 15 TIMES.
"Terminating the loop pass and continuing with the next loop pass if the condition is
"true (if the number is odd)
CHECK sy-index MOD 2 = 0.
str_d = |{ str_d }{ COND #( WHEN str_d IS NOT INITIAL THEN `, ` ) }{ sy-index }|.
ENDDO.
"str_d: 2, 4, 6, 8, 10, 12, 14
"CHECK NOT
DATA str_e TYPE string.
DO 15 TIMES.
"Here, it is checked whether the sy-index value is not an even number
CHECK NOT sy-index MOD 2 = 0.
str_e = |{ str_e }{ COND #( WHEN str_e IS NOT INITIAL THEN `, ` ) }{ sy-index }|.
ENDDO.
"str_e: 1, 3, 5, 7, 9, 11, 13, 15
"------------ EXIT ------------
DATA str_f TYPE string.
DO 15 TIMES.
"Terminating the entire loop
IF sy-index = 7.
EXIT.
ELSE.
str_f = |{ str_f }{ COND #( WHEN str_f IS NOT INITIAL THEN `, ` ) }{ sy-index }|.
ENDIF.
ENDDO.
"str_f: 1, 2, 3, 4, 5, 6
```
> **💡 Note**<br>
> - [`RETURN`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abapreturn.htm) statements immediately terminate the current processing block. However, according to the [guidelines (F1 docu for standard ABAP)](https://help.sap.com/doc/abapdocu_latest_index_htm/latest/en-US/index.htm?file=abenexit_procedure_guidl.htm), `RETURN` should only be used to exit procedures like methods.
> - `EXIT` and `CHECK` might also be used for exiting procedures. However, their use inside loops is recommended.
@@ -413,11 +499,43 @@ The following ABAP keywords are available for interrupting and exiting loops:
- Conditional loops introduced by `WHILE` and ended by `ENDWHILE` are repeated as long as a logical expression is true.
- These loops can also be exited using the statements mentioned above.
- Like in `DO` loops, the system field `sy-index` contains the number of previous loop passes including the current pass.
- Also check the conditional loops options using `FOR ... WHILE` with a constructor expression in the [Constructor Expressions](05_Constructor_Expressions.md) cheat sheet.
```abap
WHILE log_exp.
... "statement_block
DATA int_itab TYPE TABLE OF i WITH EMPTY KEY.
WHILE lines( int_itab ) = 5.
int_itab = VALUE #( BASE int_itab ( sy-index ) ).
ENDWHILE.
"Content of int_itab:
"1
"2
"3
"4
"5
"The following string replacement example uses a WHILE
"statement for demo purposes - instead of using a REPLACE ALL
"OCCURRENCES statement or the replace function to replace all
"occurrences. The WHILE loop exits when there are no more '#'
"characters to be replaced in the string. The value of the data
"object, which is checked in the logical expression, is then set
"to make the logical expression false.
DATA(str_to_replace) = `Lorem#ipsum#dolor#sit#amet`.
DATA(subrc) = 0.
DATA(counter) = 0.
WHILE subrc = 0.
REPLACE `#` IN str_to_replace WITH ` `.
IF sy-subrc <> 0.
subrc = 1.
ELSE.
counter += 1.
ENDIF.
ENDWHILE.
"str_to_replace: Lorem ipsum dolor sit amet
"counter: 4
```
<p align="right"><a href="#top">⬆️ back to top</a></p>