What is field symbols in abap
hi
what is field symbols in abap in which scenario we can use filed symbols?
Moderator message : Search for available information, thread locked.
Edited by: Vinod Kumar on Dec 16, 2011 5:11 PM
Hai,
Generally, we use the explicit work area to process the internal table like appending & modifying records. We can reduce the time and improve the performance of the program by using the field-symbols. When we use the LOOP construct with the explicit work area, system need to engage the resources to put the required record in the work area, process it and move it back to the table if the needed. This additional processing time could be saved by using the field-symbol. By using the field-symbols we can save this additional time and improve the performance. Field-symbols are similar to dereferenced pointers in C. While using the field-symbol, system uses the same memory allocated to that particular field in the record instead of moving it to work area and processing
field symbols
Edited by: Ravi.Seela on Dec 16, 2011 7:53 AM
Similar Messages
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What are field symbols and field groups.? Have you used "component idx of s
What are field symbols and field groups.? Have you used "component idx of structure"
Field Symbols and field groups
Field Groups / Extracts
http://help.sap.com/saphelp_46c/helpdata/EN/9f/db9ede35c111d1829f0000e829fbfe/frameset.htm
Field Symbols
http://help.sap.com/saphelp_46c/helpdata/EN/fc/eb387a358411d1829f0000e829fbfe/frameset.htm
Field symbols: are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to each field symbol before you can address the latter in programs.
Field Groups:
A field group is a user-defined grouping of characteristics and basic key figures from the EC-EIS or EC-BP field catalog.
Use
The field catalog contains the fields that are used in the aspects. As the number of fields grows, the field catalog becomes very large and unclear. To simplify maintenance of the aspects, you can group fields in a field group. You can group the fields as you wish, for example, by subject area or responsibility area. A field may be included in several field groups.
When maintaining the data structure of an aspect, you can select the field group that contains the relevant characteristics and basic key figures. This way you limit the number of fields offered.
A field group combines several existing fields together under one name
like
FIELD-GROUPS: fg.
then you can use one insert statement to insert values in fields of field-group.
INSERT f1 f2 ... INTO fg.
Field symbols
If u have experience with 'C', then understand this to be similar to a pointer.
It is used to reference another variable dynamically. So this field symbol will simply point to some other variable. and this pointer can be changed at runtime.
FIELD-SYMBOLS <FS>.
DATA FIELD VALUE 'X'.
ASSIGN FIELD TO <FS>.
WRITE <FS>.
Field symbols: are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to each field symbol before you can address the latter in programs.
Field Groups:
A field group is a user-defined grouping of characteristics and basic key figures from the EC-EIS or EC-BP field catalog.
Use
The field catalog contains the fields that are used in the aspects. As the number of fields grows, the field catalog becomes very large and unclear. To simplify maintenance of the aspects, you can group fields in a field group. You can group the fields as you wish, for example, by subject area or responsibility area. A field may be included in several field groups.
When maintaining the data structure of an aspect, you can select the field group that contains the relevant characteristics and basic key figures. This way you limit the number of fields offered.
Field Groups / Extracts
http://help.sap.com/saphelp_46c/helpdata/EN/9f/db9ede35c111d1829f0000e829fbfe/frameset.htm
Field Symbols
http://help.sap.com/saphelp_46c/helpdata/EN/fc/eb387a358411d1829f0000e829fbfe/frameset.htm -
What are field symbols and field groups.?
hi,
What are field symbols and field groups.? what is the usage of "component idx of structure" clause with field groups?
regardssorry, question resolved.
-
Hi all,
Can anyone explains what is Fiels symbol and significance of that with examples?
Thanks
ShivaHI Shiva
Field symbols are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to each field symbol before you can address the latter in programs.
Field symbols are similar to dereferenced pointers in C (that is, pointers to which the content operator * is applied). However, the only real equivalent of pointers in ABAP, that is, variables that contain a memory address (reference) and that can be used without the contents operator, are reference variables in ABAP Objects. (For more information, see Data References).
All operations programmed with field symbols are applied to the field assigned to it. For example, a MOVE statement between two field symbols moves the contents of the field assigned to the first field symbol to the field assigned to the second field symbol. The field symbols themselves point to the same fields after the MOVE statement as they did before.
You can create field symbols either without or with type specifications. If you do not specify a type, the field symbol inherits all of the technical attributes of the field assigned to it. If you do specify a type, the system checks the compatibility of the field symbol and the field you are assigning to it during the ASSIGN statement.
Field symbols provide greater flexibility when you address data objects:
If you want to process sections of fields, you can specify the offset and length of the field dynamically.
You can assign one field symbol to another, which allows you to address parts of fields.
Assignments to field symbols may extend beyond field boundaries. This allows you to address regular sequences of fields in memory efficiently.
You can also force a field symbol to take different technical attributes from those of the field assigned to it.
The flexibility of field symbols provides elegant solutions to certain problems. On the other hand, it does mean that errors can easily occur. Since fields are not assigned to field symbols until runtime, the effectiveness of syntax and security checks is very limited for operations involving field symbols. This can lead to runtime errors or incorrect data assignments.
While runtime errors indicate an obvious problem, incorrect data assignments are dangerous because they can be very difficult to detect. For this reason, you should only use field symbols if you cannot achieve the same result using other ABAP statements.
For example, you may want to process part of a string where the offset and length depend on the contents of the field. You could use field symbols in this case. However, since the MOVE statement also supports variable offset and length specifications, you should use it instead. The MOVE statement (with your own auxiliary variables if required) is much safer than using field symbols, since it cannot address memory beyond the boundary of a field. However, field symbols may improve
To declare a field symbol, use the statement
FIELD-SYMBOLS <FS> [<type>|STRUCTURE <s> DEFAULT <wa>].
For field symbols, the angle brackets are part of the syntax. They identify field symbols in the program code.
If you do not specify any additions, the field symbol <FS> can have data objects of any type assigned to it. When you assign a data object, the field symbol inherits its technical attributes. The data type of the assigned data object becomes the actual data type of the field symbol.
Note: it is possible to assign reference variables and structured data objects to untyped field symbols. However, the static field symbol is only a pointer to the field in memory, and does not have the complex type attributes of a reference or structured field until runtime. You can only use the field symbol to address the whole field (for example, in a MOVE statement). Specific statements such as CREATE OBJECT <FS> or LOOP AT <FS> are not possible.
Typing Field Symbols
The <type> addition allows you to specify the type of a field symbol. When you assign a data object to a field symbol, the system checks whether the type of the data object you are trying to assign is compatible with that of the field symbol. If the types are not compatible or convertible, the system reacts with a syntax or runtime error. If however, you want to assign the type of the field symbol to the data object by means of casting, you must do so explicitly using the ASSIGN statement. The system then treats the assigned data object as if it had the same type as the field symbol.
You specify the type of a field symbol using the same semantics as for formal parameters in procedures. For <type> you can enter either TYPE <t> or LIKE <f>. You can specify the type either generically or in full. If you specify a generic type, the type of the field symbol is either partially specified or not specified at all. Any attributes that are not specified are inherited from the corresponding data object in the ASSIGN statement. If you specify the type fully, all of the technical attributes of the field symbol are determined when you define it. You can then only assign data objects to it that have exactly the same data type.
You should always specify a type for each field symbol. If you cannot avoid defining a generic field symbol, make this clear by using an appropriate generic type declaration.
Generic Type Specification
The following types allow you more freedom when using actual parameters. The data object only needs to have the selection of attributes specified.
Typing
Check for data object
No type specification
TYPE ANY
All types of data object are accepted. The field symbol adopts all of the attributes of the data object.
TYPE C, N, P, or X
Only data objects with type C, N, P, or X are accepted. The field symbol adopts the field length and DECIMALS specification (type P) of the data object.
TYPE TABLE
The system checks whether the data object is a standard internal table. This is a shortened form of TYPE STANDARD TABLE (see below).
TYPE ANY TABLE
The system checks whether the data object is an internal table. The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE INDEX TABLE
The system checks whether the data object is an index table (standard or sorted table). The field symbol inherits all of the attributes (line type, table type, key) from the data object.
TYPE STANDARD TABLE
The system checks whether the data object is a standard internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE SORTED TABLE
The system checks whether the actual parameter is a sorted internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
TYPE HASHED TABLE
The system checks whether the actual parameter is a hashed internal table. The field symbol inherits all of the remaining attributes (line type, key) from the data object.
If you specify a type generically, remember that the attributes inherited by the field symbol from the program are not statically recognizable in the program. You can, at most, address them dynamically.
TYPES: BEGIN OF line,
col1 TYPE c,
col2 TYPE c,
END OF line.
DATA: wa TYPE line,
itab TYPE HASHED TABLE OF line WITH UNIQUE KEY col1,
key(4) TYPE c VALUE 'COL1'.
FIELD-SYMBOLS <fs> TYPE ANY TABLE.
ASSIGN itab TO <fs>.
READ TABLE <fs> WITH TABLE KEY (key) = 'X' INTO wa.
The internal table ITAB is assigned to the generic field symbol <FS>, after which it is possible to address the table key of the field symbol dynamically. However, the static address
READ TABLE <fs> WITH TABLE KEY col1 = 'X' INTO wa.
is not possible syntactically, since the field symbol does not adopt the key of table ITAB until runtime. In the program, the type specification ANY TABLE only indicates that <FS> is a table. If the type had been ANY (or no type had been specified at all), even the specific internal table statement READ TABLE <FS> would not have been possible.
If you adopt a structured type generically (a structure, or a table with structured line type), the individual components cannot be addressed in the program either statically or dynamically. In this case, you would have to work with further field symbols and the method of assigning structures component by component.
Specifying the Type Fully
When you use the following types, the technical attributes of the field symbols are fully specified. The technical attributes of the data objects must correspond to those of the field symbol.
Typing
Technical attributes of the field symbol
TYPE D, F, I, or T
The field symbol has the technical attributes of the predefined elementary type
TYPE <type>
The field symbol has the type <type>. This is a data type defined within the program using the TYPES statement, or a type from the ABAP Dictionary
TYPE REF TO <cif>|DATA
The field symbol is a reference variable for the class or interface <cif>, or for a data object.
TYPE LINE OF <itab>
The field symbol has the same type as a line of the internal table <itab> defined using a TYPES statement or defined in the ABAP Dictionary
LIKE <f>
The field symbol has the same type as an internal data object <f> or structure, or a database table from the ABAP Dictionary
When you use a field symbol that is fully typed, you can address its attributes statically in the program, since they are recognized in the source code. If you fully specify the type of a field symbol as a reference or structured data object, you can address it as you would the data object itself, once you have assigned an object to it. So, for example, you could address the components of a structure, loop through an internal table, or create an object with reference to a field symbol.
REPORT demo_field_symbols_type .
DATA: BEGIN OF line,
col1(1) TYPE c,
col2(1) TYPE c VALUE 'X',
END OF line.
FIELD-SYMBOLS <fs> LIKE line.
ASSIGN line TO <fs>.
MOVE <fs>-col2 TO <fs>-col1.
The field symbol <FS> is fully typed as a structure, and you can address its components in the program.
Attaching a structure to a field symbol
The STRUCTURE addition forces a structured view of the data objects that you assign to a field symbol.
FIELD-SYMBOLS <FS> STRUCTURE <s> DEFAULT <f>.
The structure <s> is either a structured local data object in the program, or a flat structure from the ABAP Dictionary. <f> is a data object that must be assigned to the field symbol as a starting field. However, this assignment can be changed later using the ASSIGN statement.
When you assign a data object to the field symbol, the system only checks that it is at least as long as the structure. You can address the individual components of the field symbol. It has the same technical attributes as the structure <s>.
If <s> contains components with type I or F, you should remember the possible effects of alignment. When you assign a data object to a field symbol with a structure, the data object must have the same alignment, otherwise a runtime error may result. In such cases, you are advised to assign such data objects only to structured field symbols, which retain the same structure as the field symbol at least over the length of the structure.
The STRUCTURE is obsolete; you should no longer use it. Field symbols defined using the STRUCTURE addition are a mixture of typed field symbols and a utility for casting to either local or ABAP Dictionary data types. If you want to define the type of a field symbol, include the TYPE addition in a FIELD-SYMBOLS statement. If you want to use casting, include the CASTING addition in an ASSIGN statement.
Example using the obsolete STRUCTURE addition:
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
col1(2),
col2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> STRUCTURE line1 DEFAULT wa,
<f2> STRUCTURE line2 DEFAULT wa.
WRITE: / <f1>-col1, <f1>-col2, <f1>-col3,
/ <f2>-col1, <f2>-col2.
Example using the correct syntax (TYPE and CASTING):
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
COL1(2),
COL2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> LIKE line1.
ASSIGN wa TO <f1> CASTING.
FIELD-SYMBOLS: <f2> LIKE line2.
ASSIGN wa TO <f2> CASTING.
WRITE: / <f1>-col1, <F1>-col2, <F1>-col3,
/ <f2>-col1, <F2>-col2.
In both cases, the list appears as follows:
012 34 56789
01 2345/67/89
This example declares two field symbols to which different structures are attached. The string WA is then assigned to each of them. The output shows that the field symbols assign the strings component by component according to the type of the components.
Assigning Components of Structures to a Field Symbol
For a structured data object <s>, you can use the statement
ASSIGN COMPONENT <comp> OF STRUCTURE <s> TO <FS>.
to assign one of its components <comp> to the field symbol <FS>. You can specify the component <comp> either as a literal or a variable. If <comp> is of type C or a structure that has no internal tables as components, it specifies the name of the component. If <comp> has any other elementary data type, it is converted to type I and specifies the number of the component. If the assignment is successful, SY-SUBRC is set to 0. Otherwise, it is set to 4.
This statement is particularly important for addressing components of structured data objects dynamically. If you assign a data object to a field symbol either generically or using casting, or pass it generically (or using casting) to the parameter interface of a procedure, you cannot address its components either statically or dynamically. Instead, you must use the above statement. This allows indirect access either using the component name or its index number.
DATA: BEGIN OF LINE,
COL1 TYPE I VALUE '11',
COL2 TYPE I VALUE '22',
COL3 TYPE I VALUE '33',
END OF LINE.
DATA COMP(5) VALUE 'COL3'.
FIELD-SYMBOLS: <F1>, <F2>, <F3>.
ASSIGN LINE TO <F1>.
ASSIGN COMP TO <F2>.
DO 3 TIMES.
ASSIGN COMPONENT SY-INDEX OF STRUCTURE <F1> TO <F3>.
WRITE <F3>.
ENDDO.
ASSIGN COMPONENT <F2> OF STRUCTURE <F1> TO <F3>.
WRITE / <F3>.
The output is:
11 22 33
33
The field symbol <F1> points to the structure LINE, <F2> points to the field COMP. In the DO loop, the components of LINE are specified by their numbers and assigned one by one to <F3>. After the loop, the component COL3 of LINE is specified by its name and assigned to <F3>. Note that ASSIGN COMPONENT is the only possible method of addressing the components of <F1>. Expressions such as <F1>-COL1 are syntactically incorrect.
Regards,
Laxmi. -
What is Field Symbols & How to Use it in Programs ?
I am working in Abap ,for 2 yrs now i want work with Field Symbols .
Sathya<link_farm_and_everything_else_removed_by_moderator>
Edited by: Julius Bussche on Sep 3, 2008 8:59 AM -
ABAP Objects v/s Field Symbols
Hi,
My query is:
In ABAP Objects, reference variables can be assigned to each other.
We can also assign the reference variable to a field symbol.
Does that mean, that we can achieve the same functionality(like accessing a method of the class) using the field-symbols?
If so, why not use field-symbols instead of objects? What are the other differences?
Please provide your opinions.
Regards
s.a.kHi,
We can have any number of Field Symbols refering to One Variable or Object, but all these Field symbols refer to same memory location they donto have individual memory locations.
Where are in Object, if diffrent objected are created refreing to one object all the objects have diffrent memory locations.
Read the documentation of Field symbols and ABAP Objects you will get the clear diffrene.
Regards,
Kumar M. -
Field symbols and field groups
Hi friends plz send me the answer for this query:
What are field symbols and field groups.? what is the"component idx of structure" clause with field groups?Hi,
A field group combines several existing fields together under one name
like
FIELD-GROUPS: fg.
then you can use one insert statement to insert values in fields of field-group.
INSERT f1 f2 ... INTO fg.
Field symbols
If u have experience with 'C', then understand this to be similar to a pointer.
It is used to reference another variable dynamically. So this field symbol will simply point to some other variable. and this pointer can be changed at runtime.
FIELD-SYMBOLS <FS>.
DATA FIELD VALUE 'X'.
ASSIGN FIELD TO <FS>.
WRITE <FS>.
Field symbols: are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to each field symbol before you can address the latter in programs.
Field Groups:
A field group is a user-defined grouping of characteristics and basic key figures from the EC-EIS or EC-BP field catalog.
Use
The field catalog contains the fields that are used in the aspects. As the number of fields grows, the field catalog becomes very large and unclear. To simplify maintenance of the aspects, you can group fields in a field group. You can group the fields as you wish, for example, by subject area or responsibility area. A field may be included in several field groups.
When maintaining the data structure of an aspect, you can select the field group that contains the relevant characteristics and basic key figures. This way you limit the number of fields offered.
Field Groups / Extracts
http://help.sap.com/saphelp_46c/helpdata/EN/9f/db9ede35c111d1829f0000e829fbfe/frameset.htm
Field Symbols
http://help.sap.com/saphelp_46c/helpdata/EN/fc/eb387a358411d1829f0000e829fbfe/frameset.htm
Regards,
Priyanka. -
What are field symbols and field groups.? Have you used "component idx of structure" clause with field groups?
Hi
this will help you
reward if usefull
<b><u>FIELD-SYMBOLS</u></b>
<u>Syntax</u>
FIELD-SYMBOLS <fs> { typing | STRUCTURE struc DEFAULT dobj }.
Extras:
1. ... typing
2. ... STRUCTURE struc DEFAULT dobj
The FIELD-SYMBOLS statement declares a field symbol <fs>. The name conventions apply to the name fs. The angle brackets of the field symbols indicate the difference to data objects and are obligatory. You can declare field symbols in any procedure and in the global declaration section of an ABAP program, but not in the declaration section of a class or an interface. You can use a field symbol in any operand position in which it is visible and which match the typing defined using typing.
After its declaration, a field symbol is initial - that is, it does not reference a memory area. You have to assign a memory area to it (normally using the ASSIGN statement) before you can use it as an operand. Otherwise an exception will be triggered.
<b><u>FIELD-GROUPS</u></b>
<u>Syntax</u>
FIELD-GROUPS { header | field_group }.
Declaration of a field group for the extract dataset of the program. Each field group represents the name of a line structure of the extract dataset. You can create as many field groups as you wish in a program. You define the actual components of a field group with the statement INSERT.
The denominator of a field group is either the predefined name header or any name field_group. If you declare a field group header, it automatically becomes the beginning part of all remaining field groups of the program and its components constitute the standard sort key of the extract dataset for the statement SORT.
The statement FIELD-GROUPS is possible in the global declaration-part of an ABAP program, as well as in the subprograms and function modules. Field groups that are declared in procedures are visible only there.
As you can only define global data objects as components of field groups with the statement INSERT, we recommend to declare field groups only in the global declaration part as well. -
hiiiii friends..
i m new to this website...
plz do help to grow in this abap field..
what is field symbols and use of this ??
diffrence between hide and get cursor in the interactive report..Field Symbols:
Field symbols are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Ex:-
DATA: wa(10) VALUE '0123456789'.
DATA: BEGIN OF line1,
col1(3),
col2(2),
col3(5),
END OF line1.
DATA: BEGIN OF line2,
col1(2),
col2 LIKE sy-datum,
END OF line2.
FIELD-SYMBOLS: <f1> STRUCTURE line1 DEFAULT wa,
<f2> STRUCTURE line2 DEFAULT wa.
WRITE: / <f1>-col1, <f1>-col2, <f1>-col3,
/ <f2>-col1, <f2>-col2.
HIDE:
The HIDE statement is one of the fundamental statements for interactive reporting. You use the HIDE technique when creating a basic list. It defines the information that can be passed to subsequent detail lists.
Ex: See demo_list_read_line Program in SE38
GET CURSOR:
Use the statements GET CURSOR FIELD and GET CURSOR LINE to pass the output field or output line on which the cursor was positioned during the interactive event to the ABAP program.
Ex:
See SAPMZTST Program in SE38.
Plz Reward if help,
Mahi. -
Hi
How can i use the fields-symbols in Abap Object (class)?: The program <b>SAPLMIGO</b> have a table <b>oref_detail->t_goserial</b>. I would get this table in my program (not object) by using field-symbol
What can i do?
it's urgent
thanks a lotHello
Here are the fact:
(1) oref_detail is of TYPE REF TO lcl_migo_detail (local class)
* Detail
oref_detail TYPE REF TO lcl_migo_detail, (lines 244-245 in LMIGOTOP)
(2) Here is the definition of the local class (LMIGODC1):
* INCLUDE LMIGODC1 *
* Detail carrier (data manager)
CLASS lcl_migo_detail DEFINITION
INHERITING FROM lcl_migo_screenobject.
PUBLIC SECTION.
INTERFACES:
lif_migo_frame.
DATA:
* Line in the model which is currently displayed
current_line TYPE sytabix READ-ONLY,
* table for working with serial numbers internally
t_goserial TYPE lcl_migo_kernel=>ty_t_goserial,
" need to be changed when friend
" concept is available
* table for working with freight vendors internally
t_gofreight TYPE TABLE OF gofreight." need to be changed when friend
" concept is availible
METHODS:
constructor,
pbo REDEFINITION,
pbo_godynpro_fill,
pai REDEFINITION,
pai_get,
pai_transfer_fields_fill,
line_find. "ON REQUEST
PRIVATE SECTION.
DATA:
p_global_counter TYPE goitem-global_counter, "old gobal_counter
"(before sort/Not OK)
p_last_new_line_mode TYPE char1,
poref_settings TYPE REF TO cl_mmim_userdefaults,
ps_old_goitem TYPE goitem. "goitem before PAI-field transport
METHODS:
transfer_item_copy.
ENDCLASS. "lcl_migo_detail DEFINITIO
(3) t_goserial has the following definition (include LMIGOKE1):
* Serial number with SELECTED-flag
BEGIN OF ty_s_goserial,
selected TYPE xfeld,
serialno TYPE gernr,
END OF ty_s_goserial,
ty_t_goserial TYPE STANDARD TABLE OF ty_s_goserial WITH
NON-UNIQUE DEFAULT KEY,
What does it mean that you want to "access" this internal table? Do you need this itab within a userexit or BAdI?
Regards
Uwe -
Hi
How can i use the fields-symbols in Abap Object (class)?: The program <b>SAPLMIGO</b> have a table <b>oref_detail->t_goserial</b>. I would get this table in my program (not object) by using field-symbol
What can i do?
it's urgent
thanks a lotHi,
You can try this
field-symbols: <tab> type table.
create object o ...
assign o->t_values to <tab>.
You need to create the object. -
The difference between FIELD-SYMBOL and normal DATA TYPE
Dear experts,
Please see the example below, both are output the same result.
DATA: EXTERNAL_RECORD(4000),
POSITION TYPE I,
LENGTH TYPE N,
ENTRY TYPE STRING.
EXTERNAL_RECORD = '0005Smith0007Edwards0005Young'.
DO.
LENGTH = EXTERNAL_RECORD+POSITION(4).
IF LENGTH = 0.
EXIT.
ENDIF.
ADD 4 TO POSITION.
MOVE EXTERNAL_RECORD+POSITION(LENGTH) TO ENTRY.
WRITE ENTRY.
ADD LENGTH TO POSITION.
IF POSITION >= 4000.
EXIT.
ENDIF.
ENDDO.
--OR It can be written as--
DATA: EXTERNAL_RECORD(4000),
POSITION TYPE I,
LENGTH TYPE N.
FIELD-SYMBOLS <ENTRY>.
EXTERNAL_RECORD = '0005Smith0007Edwards0005Young'.
DO.
LENGTH = EXTERNAL_RECORD+POSITION(4).
IF LENGTH = 0.
EXIT.
ENDIF.
ADD 4 TO POSITION.
ASSIGN EXTERNAL_RECORD+POSITION(LENGTH) TO <ENTRY>.
WRITE <ENTRY>.
ADD LENGTH TO POSITION.
IF POSITION >= 4000.
EXIT.
ENDIF.
ENDDO.
Is there any special circumstances we need to use FIELD-SYMBOL?
Why is FIELD-SYMBOL is introduce in the first place?
Kindly advice with example.
Thanks in advance for those who can help me on this.HI,
You can use field symbols to make the program more dynamic. In this example the name of a table control is substituted by a field symbol. Thus you cal call the form with any internal table, using the name of the table control as a parameter.
Example
form insert_row
using p_tc_name.
field-symbols <tc> type cxtab_control. "Table control
assign (p_tc_name) to <tc>.
insert 100 lines in table control
<tc>-lines = 100.
Field symbols allow you to:
** Assign an alias to a data object(for example, a shortened
name for data objects structured through several hierarchies
- <fs>-f instead of rec1-rec2-rec3-f)
** Set the offset and length for a string variably at runtime
** Set a pointer to a data object that you determine at runtime (dynamic ASSIGN)
** Adopt or change the type of a field dynamically at runtime
** Access components of a structure
** (from Release 4.5A) Point to lines of an internal table
(process internal tables without a separate work area)
Field symbols in ABAP are similar to pointers in other programming
languages. However, pointers (as used in PASCAL or C) differ from ABAP
field symbols in their reference syntax.
The statement ASSIGN f to <fs> assigns the field f to field
symbol <fs>. The field symbol <fs> then "points" to the
contents of field f at runtime. This means that all changes to the
contents of f are visible in <fs> and vice versa. You declare
the field symbol <fs> using the statement FIELD-SYMBOLS: <fs>.
Reference syntax
Programming languages such as PASCAL and C use a dereferencing symbol
to indicate the difference between a reference and the object to which
it refers; so PASCAL would use p^ for a pointer instead of p, C would
use *p instead of p. ABAP does not have any such dereferencing symbol.
** In PASCAL or C, if you assign a pointer p1 to a pointer p2,
you force p1 to point to the object to which p2 refers (reference semantics).
** In ABAP, if you assign a field symbol <fs1> to a field
symbol <fs2>, <fs1> takes the value of the data object to
which <fs2> refers (value semantics).
** Field symbols in ABAP are always dereferenced, that is,
they always access the referenced data object. If you want to
change the reference yourself in ABAP, you can use the ASSIGN statement
to assign field symbol <fs1> to field symbol <fs2>.
Using field symbols
You declare field symbols using the FIELD-SYMBOLS statement.
They may be declared either with or without a specific type.
At runtime you assign a field to the field symbol using the ASSIGN
statement. All of the operations on the field symbol act on the field
assigned to it.
When you assign a field to an untyped field symbol, the field symbol
adopts the type of the field. If, on the other hand, you want to assign
a field to a typed field symbol, the type of the field and that of the
field symbol must be compatible.
A field symbol can point to any data object and from Release 4.5A,
they can also point to lines of internal tables.
The brackets (<>) are part of the syntax.
Use the expression <fs> IS ASSIGNED to find out whether the field
symbol <fs> is assigned to a field.
The statement UNASSIGN <fs> sets the field symbol <fs> so
that it points to nothing. The logical expression <fs>
IS ASSIGNED is then false. The corresponding negative expression
is IF NOT <fs> IS ASSIGNED.
An unassigned field symbol <fs> behaves as a constant with
type C(1) and initial value SPACE.
MOVE <fs>
TO dest Transfers the initial value SPACE to the variable dest
MOVE 'A' to <fs>
Not possible, since <fs> is a constant
(runtime error).
To lift a type restriction, use the CASTING addition in the
ASSIGN statement. The data object is then interpreted as though
it had the data type of the field symbol. You can also do this
with untyped field symbols using the CASTING TYPE <type> addition.
The danger with pointers is that they may point to invalid areas.
This danger is not so acute in ABAP, because the language does not
use address arithmetic (for example, in other languages, pointer p
might point to address 1024. After the statement p = p + 10, it would
point to the address 1034). However, the danger does still exist, and
memory protection violations lead to runtime errors.
A pointer in ABAP may not point beyond a segment boundary. ABAP does
not have one large address space, but rather a set of segments.
Each of the following has its own segment:
* All global data
* All local data
* Each table work area (TABLES)
* Each COMMON PART
You should only let field symbols move within an elementary field or
structure where ABAP allows you to assign both within the global data
and beyond a field boundary.
Rgds
Umakanth -
Fields symbols and field groups
what are field symbols and field groups?
Regards,
sravanthiDifference between Field symbols and Field groups
what are field groups and field symbols ... -
Hi All,
Can anyone explain fully about field symbols in ABAP.
please provide with examples how to use in programming.
Thanks in advance.
Naba.Field Symbols
Field symbols are placeholders or symbolic names for other fields. They do not physically reserve space for a field, but point to its contents. A field symbol cam point to any data object. The data object to which a field symbol points is assigned to it after it has been declared in the program.
Whenever you address a field symbol in a program, you are addressing the field that is assigned to the field symbol. After successful assignment, there is no difference in ABAP whether you reference the field symbol or the field itself. You must assign a field to a field symbol before you can address it in a program.
Field symbols are similar to de-referenced pointers in the C programming language (that is, pointers to which the content operator * is applied). In ABAP, data references represent a real equivalent to pointers in the sense of variables that contain a memory address and can be used without the contents operator.
All operations programmed with field symbols are applied to the field assigned to it. A MOVE statement between two field symbols, for example, assigns the contents of the field assigned to another source field symbol to the field assigned to the target field symbol. The field symbols themselves point to the same fields after the MOVE statement as they did before the MOVEstatement.
You can create field symbols either without or with type specifications. If you do not specify a type, the field symbol inherits all of the technical attributes of the field assigned to it. If you do specify a type, the system checks during the field assignment whether the assigned field matches the type of field symbol.
Field symbols provide greater flexibility when you address data objects:
· You can assign one field symbol to another, which allows you to address subfields.
· Assignments to field symbols may extend beyond field boundaries. This allows you to address regular sequences of fields in memory efficiently.
· You can also force a field symbol to take different technical properties than those of the field assigned to it (casting).
The flexibility of field symbols provides elegant solutions to certain problems. On the other hand, it does mean that errors can easily occur. Since fields are not assigned to field symbols until runtime, the effectiveness of syntax and security checks is very limited for operations involving field symbols. This can lead to runtime errors or incorrect data assignments.
While runtime errors indicate an obvious problem, incorrect data assignments are dangerous because they can be very difficult to detect. For this reason, you should only use field symbols if you cannot achieve the same result using other ABAP statements.
For example, you may want to process part of a string where the offset and length depend on the contents of the field. You could use field symbols in this case. The MOVE statement (with your own auxiliary variables, if required) is much safer than using field symbols, since it cannot address memory beyond the boundary of a field. However, field symbols may improve performance in some cases.
*& Chapter 24: Working with Field Symbols
REPORT CHAP2401.
Defining a Field Symbol
FIELD-SYMBOLS .
Variable for later use
DATA FIELD VALUE 'X'.
Assigning a field to a Field Symbol
ASSIGN FIELD TO .
Using a Field Symbol which has an assigned field
WRITE . -
Field-symbols v/s Object references in OO-ABAP
Hi,
can anyone please tell me what is the difference between using field-symbols and object references in OO ABAP? Is there a specific need for field-symbols now that we have references?
Thanks.
Shakul.Hi ,
Please note that both Field symbols & Object References are different .
You can use Field symbols during the following situations
1) When you want to modify the value of internal table, the field symbol would be useful since you do not have to use any Modify statement as in case of work area. The Field symbol works as a pointer and any changes to the field symbol will directly affect the value of the internal table
2) Make sure that you do not reassign the field symbol within a Loop iteration
3) Field symbols are useful when you work with dynamic internal tables ( tables whose structure is determined during run time)
4) After Read an internal table ( Read itab...) into a Field symbol, make sure you do a Sy-subrc check or check if the field symbol is assigned.IF not this will give you a run time error
You can use Object References while creating an object to a class. They are instances of a class.
Thanks,
Chakram Govindarajan
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