A field symbol is a pointer that allows direct access to a row of an internal table without copying it to a work area. Using a field symbol for internal table row access has some advantages over using a work area, such as12:
* A MODIFY statement to write changed contents back to the table is not required: This is true. When you use a work area, you have to copy the row content from the internal table to the work area, modify it, and then copy it back to the internal table using the MODIFY statement. This can be costly in terms of performance and memory consumption. When you use a field symbol, you can modify the row content directly in the internal table without any copying. Therefore, you do not need the MODIFY statement12.
* Using a field symbol is faster than using a work area: This is true. As explained above, using a field
* symbol avoids the overhead of copying data between the internal table and the work area. This can improve the performance of the loop considerably, especially for large internal tables. According to some benchmarks, using a field symbol can save 25-40% of the runtime compared to using a work area12.
You cannot do any of the following:
* The field symbol can be reused for other programs: This is false. A field symbol is a local variable that is only visible within the scope of its declaration. It cannot be reused for other programs unless it is declared globally or passed as a parameter. Moreover, a field symbol must have the same type as the line type of the internal table that it accesses. Therefore, it cannot be used for any internal table with a different line type12.
* The row content is copied to the field symbol instead to a work area: This is false. As explained above, using a field symbol does not copy the row content to the field symbol. Instead, the field symbol points to the memory address of the row in the internal table and allows direct access to it. Therefore, there is no copying involved when using a field symbol12.
References: 1: Using Field Symbols to Process Internal Tables - SAP Learning 2: Access to Internal Tables - ABAP Keyword Documentation - SAP Online Help