About abap

Question

hai,
     now iam learning sap i want operations performed on internal table.

Answer 1

An internal table is a run time instance.  It get created when program starts execution. It get destroyed when program terminates. it has two different parts.  Header Line(optional) & Body(Compulsory).
Any value that comes to or goes from interanal table , that travels through headerline.
<b>*A related program is .</b>
<b>*declaration</b>.
data: begin of inernaltable occurs 0,
         x type c,
         y type i,
      end of itab.
<b>*initializing headerline</b>  
internaltable-x = 'd'.
   internaltable-y = 34.
<b>*storing value into internal table</b>
append internaltable . 
append internaltable .
append internaltable .
<b>*reading internal table</b>
loop at itab .
   write: / internaltable-x, internaltable-y.  "writes to output list
endloop.
<b>Fields of Internal Tables</b>
<b>SY-TABIX</b>
Current line of an internal table. SY-TABIX is set by the statements below, but only for index tables. The field is either not set or is set to 0 for hashed tables. 
<b>APPEND</b> sets SY-TABIX to the index of the last line of the table, that is, it contains the overall number of entries in the table. 
<b>COLLECT</b> sets SY-TABIX to the index of the existing or inserted line in the table. If the table has the type HASHED TABLE, SY-TABIX is set to 0.
<b>LOOP AT</b> sets SY-TABIX to the index of the current line at the beginning of each loop lass. At the end of the loop, SY-TABIX is reset to the value that it had before entering the loop. It is set to 0 if the table has the type HASHED TABLE. 
<b>READ TABLE</b> sets SY-TABIX to the index of the table line read. If you use a binary search, and the system does not find a line, SY-TABIX contains the total number of lines, or one more than the total number of lines. SY-INDEX is undefined if a linear search fails to return an entry. 
<b>SEARCH</b> <itab> FOR sets SY-TABIX to the index of the table line in which the search string is found.
<b>SY-TFILL</b>
After the statements DESCRIBE TABLE, LOOP AT, and READ TABLE, SY-TFILL contains the number of lines in the relevant internal table. 
<b>SY-TLENG</b>
After the statements DESCRIBE TABLE, LOOP AT, and READ TABLE, SY-TLENG contains the length of the lines in the relevant internal table. 
<b>SY-TOCCU</b>
After the statements DESCRIBE TABLE, LOOP AT, and READ TABLE, SY-TLENG contains the initial amount of memory allocated to the relevant internal table.
Reward points if helpful.