From d40807c68dc38ab0ba1452f8d0620ee1accd828f Mon Sep 17 00:00:00 2001 From: danrega <16720986+danrega@users.noreply.github.com> Date: Thu, 2 May 2024 16:52:38 +0200 Subject: [PATCH] Update --- 13_Program_Flow_Logic.md | 220 ++++++++++++++++++++++++------- 19_ABAP_for_Cloud_Development.md | 1 + 2 files changed, 170 insertions(+), 51 deletions(-) diff --git a/13_Program_Flow_Logic.md b/13_Program_Flow_Logic.md index b420513..47f8d41 100644 --- a/13_Program_Flow_Logic.md +++ b/13_Program_Flow_Logic.md @@ -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 ) ... ```

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@@ -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.` ). ```

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@@ -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**
> - [`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 ```

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diff --git a/19_ABAP_for_Cloud_Development.md b/19_ABAP_for_Cloud_Development.md index 96b977b..d5c85dc 100644 --- a/19_ABAP_for_Cloud_Development.md +++ b/19_ABAP_for_Cloud_Development.md @@ -176,6 +176,7 @@ It provides references to more detailed information on the topic. - ABAP Keyword Documentation - [Rules for ABAP Cloud](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenabap_strict_rules.htm) - [Language Elements in ABAP Versions](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenrestricted_abap_elements.htm): A table showing which ABAP language elements are allowed in which ABAP language version + - [Contract Rules for ABAP Released APIs](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenrestricted_apis.htm)

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