How to find number of lines in an internal table

Question

Dear all,
how to find number of records present in an internal table.

Answer 1

DESCRIBE TABLE
Syntax
DESCRIBE TABLE itab [KIND knd] [LINES lin] [OCCURS n].
Extras:
1. ... KIND knd
2. ... LINES lin
3. ... OCCURS n
Effect
This statement determines some properties of the internal table itab and assigns them to the specified variables. The various additions enable you to determine the table type, the number of currently filled rows and the initial memory requirement.
In addition, the system fields sy-tfill and sy-tleng are filled with the current number of table rows and the length of a table row in bytes.
Notes
For detailed information about an internal table, you should use the methods of RTTS of the DESCRIBE TABLE statement.
Without the specification of an addition, the statement DESCRIBE TABLE only sets the system fields sy-tfill and sy-tleng.
Addition 1
... KIND knd
Effect
The table type of the internal table itab is determined and a corresponding one-digit identification is assigned to the data object knd. A character-type data type is expected for the data object. The identifications are "T" for standard tables, "S" for sorted tables and "H" for hashed tables. These values are also defined as constants sydes_kind-standard, sydes_kind-sorted, and sydes_kind-hashed in the type group SYDES.
Addition 2
... LINES lin
Effect
The current number of table rows of the internal table itab is determined and is assigned to the data object lin.The data type i is expected for the data object.
Note
As of release 6.10, the current number of rows of an internal table can also be determined using the in-built function lines.
Addition 3
... OCCURS n
Effect
The initial memory requirement defined during the creation of the internal table with the addition INITIAL SIZE or the obsolete addition OCCURS is determined and assigned to the data object n. The data type i is expected for the data object.
Example
Descending sorting of a generically typed internal table in a subprogram. Since sorted tables cannot be sorted in a descending order, the table type is checked to avoid an exception that cannot be handled.
TYPE-POOLS sydes.
FORM sort_descending CHANGING itab TYPE ANY TABLE.
  DATA tabkind(1) TYPE c.
  DESCRIBE TABLE itab KIND tabkind.
  IF tabkind = sydes_kind-standard OR
     tabkind = sydes_kind-hashed.
    SORT itab DESCENDING.
  ELSEIF tabkind = sydes_kind-sorted.
    MESSAGE '...' TYPE 'E'.
  ELSE.
    MESSAGE '...' TYPE 'E'.
  ENDIF.
ENDFORM.
DESCRIBE FIELD INTO
Note
This statement is for internal use only.
It cannot be used in application programs.
Syntax
DESCRIBE FIELD dobj INTO td.
Effect
All characteristics of the field f, its components , sub-components etc. are displayed in the field td (type description). td has to be of the type SYDES_DESC, defined in Type Group SYDES. Because of this, the type group SYDES must be integrated into the ABAP-program with a TYPE-POOLS statement .
The structure SYDES_DESC has two table-type components TYPES and NAMES:
In TYPES, the tree structure of the type belonging to f is displayed. The components of a node are stored in the table TYPES in a continuous manner. Beginning and end of the line area that represents the components are stored in TYPES-FROM and TYPES-TO. The reference to the superior node can be found in TYPES-BACK. If no superior resp. subordinate node exists, then this is marked by the value 0 (For the relevance of further components, refer to the following sections).
The names of components, types etc. are not stored directly in TYPES. Instead, the components TYPES-IDX_... hold an index in the name table NAMES. The value 0 indicates that there is no reference to the name table.
NAMES contains the possibly fragmented names in the component NAMES-NAME. If a name continues in the following line, this is indicated by an asterisk ('*') in the component NAMES-CONTINUE.
The type description table (TYPES) not only stores information about the tree structure but also further information about the type of f resp. its components. This includes especially all information that can be determined using the usual additions to DESCRIBE FIELD. In detail, TYPES contains the following columns:
IDX_NAME
Component Name
IDX_USER_TYPE
Name of a user-defined type, i.e., a type that was defined through its TYPES-statement. Derived types (... TYPE A-B) and structures from the ABAP-Dictionary are not considered to be user-defined types.
CONTEXT
For user-defined types only: The context, in which the type is defined. Possible values are defined in the constant SYDES_CONTEXT of the type group SYDES. Please only use these constants to carry out a comparison. In detail, we distinguish between the following type contexts:
SYDES_CONTEXT-PROGRAM: Program-global type
SYDES_CONTEXT-FORM   : FORM-local type
SYDES_CONTEXT-FUNCTION: FUNCTION-local type
SYDES_CONTEXT-METHOD : METHOD-local type
IDX_CONTEXT_NAME
For user-defined types only:
With a local context: The name of the FORM or FUNCTION, whose type was defined. The name of the associated program is then the first entry in the name table.
With a global context: The name of the program in which the type was defined.
IDX_EDIT_MASK
Conversion routine from the ABAP-Dictionary, is in accordance with the addition EDIT MASK at simple DESCRIBE.
IDX_HELP_ID
Help-Id when referencing to fields from the ABAP-Dictionary
LENGTH
Internal length, corresponds to the addition LENGTH at simple DESCRIBE
OUTPUT_LENGTH
Output length, corresponds to the addition OUTPUT-LENGTH at simple DESCRIBE
DECIMALS
Number of decimal digits, corresponds to the addition DECIMALS at simple DESCRIBE
TYPE
ABAP-Type, corresponds to the addition TYPE at simple DESCRIBE
TABLE_KIND
A table type is stored here for the components which represent an internal table. The same values are returned as with the variant DESCRIBE TABLE itab KIND k. Components which do not represent a table get the return value set to SYDES_KIND-UNDEFINED (see type group SYDES).
Example
Example definition of the complex data type EMPLOYEE_STRUC:
PROGRAM DESCTEST.
TYPES: BEGIN OF name_struc,
         first  TYPE c LENGTH 20,
         last   TYPE c LENGTH 20,
       END OF name_struc,
       BEGIN OF absence_time_struc,
         day        TYPE d,
         from       TYPE t,
         to         TYPE t,
       END OF absence_time_struc,
       phone_number TYPE n LENGTH 20,
       BEGIN OF employee_struc,
         id         LIKE sbook-customid,
         name       TYPE name_struc,
         BEGIN OF address,
           street  TYPE c LENGTH 30,
           zipcode TYPE n LENGTH 4,
           place   TYPE c LENGTH 30,
         END OF address,
         salary_per_month TYPE p LENGTH 10 DECIMALS 3,
         absent           TYPE STANDARD TABLE OF absence_time_struc
                               WITH NON-UNIQUE DEFAULT KEY,
         phone            TYPE STANDARD TABLE OF phone_number
                               WITH NON-UNIQUE DEFAULT KEY,
       END OF employee_struc.
You can determine the structure of the type EMPLOYEE_STRUC by collecting the type group SYDES as follows:
TYPE-POOLS: sydes.
DATA: employee TYPE employee_struc,
      td       TYPE sydes_desc.
DESCRIBE FIELD employee INTO td.
The following table shows a few selected columns of the type description table TD-TYPES. For a better overview, the names of the columns IDX_NAME, IDX_UERR_TYPE and IDX_EDIT_MASK have been shortened:
    |FROM| TO |BACK|NAME|UTYP|EMSK|TYPE
|--||||||--
  1 |  2 |  7 |  0 |  0 |  2 |  0 |  v
  2 |  0 |  0 |  1 |  6 |  0 |  4 |  N
  3 |  8 |  9 |  1 |  7 |  5 |  0 |  u
  4 | 10 | 12 |  1 |  8 |  0 |  0 |  u
  5 |  0 |  0 |  1 |  9 |  0 |  0 |  P
  6 | 13 | 13 |  1 | 11 |  0 |  0 |  h
  7 | 17 | 17 |  1 | 12 |  0 |  0 |  h
  8 |  0 |  0 |  3 | 13 |  0 |  0 |  C
  9 |  0 |  0 |  3 | 14 |  0 |  0 |  C
10 |  0 |  0 |  4 | 15 |  0 |  0 |  C
11 |  0 |  0 |  4 | 16 |  0 |  0 |  N
12 |  0 |  0 |  4 | 17 |  0 |  0 |  C
13 | 14 | 16 |  6 |  0 | 18 |  0 |  u
14 |  0 |  0 | 13 | 20 |  0 |  0 |  D
15 |  0 |  0 | 13 | 21 |  0 |  0 |  T
16 |  0 |  0 | 13 | 22 |  0 |  0 |  T
17 |  0 |  0 |  7 |  0 |  0 |  0 |  N
Please note that the entries in rows 6 and 7 represent internal tables (ABAP-Type h). There is always an entry for the corresponding row type (rows 13 and 17) to an internal table.
The indices in the rows 5 to 7 refer to entries in the name table TD-NAMES. If you look, e.g., at row 3, you find the corresponding component name in TD-NAMES from row 7 (NAME) onward and the corresponding user type from row 5 (NAME_STRUC) onward.
In the name table TD-NAMES you find the following entries. Note that the names SALARY_PER_MONTH and ABSENCE_TIME_STRUC are stored in two parts:
    |CONTINUE|NAME                   |CONTINUE|NAME
|--|     -||--
  1 |        |DESCTEST            12 |        |PHONE
  2 |        |EMPLOYEE_STRUC      13 |        |FIRST
  3 |        |SBOOK-CUSTOMID      14 |        |LAST
  4 |        |==ALPHA             15 |        |STREET
  5 |        |NAME_STRUC          16 |        |ZIPCODE
  6 |        |ID                  17 |        |PLACE
  7 |        |NAME                18 |   *    |ABSENCE_TIME_ST
  8 |        |ADDRESS             19 |        |RUC
  9 |   *    |SALARY_PER_MONT     20 |        |DAY
10 |        |H                   21 |        |FROM
11 |        |ABSENT              22 |        |TO