You want to read a single line of an internal table using table expression itab[ ...]. How can you identify the line?

The approach to reading a single line of an internal table using the table expression itab[...] involves identifying the line in a clear and efficient manner. The correct method includes specifying a free table key, which allows you to access lines in the internal table based on the values of specific fields.

In SAP ABAP, a free table key means that you can reference data not only by its numerical index but by one or more field values that match the specified key. This provides flexibility in accessing the required line, especially in scenarios where you want to retrieve a record that meets certain criteria rather than relying on the order of records in the internal table. Using a free table key supports greater maintainability and scalability in your code.

In contrast, specifying the line index directly accesses a particular position, which may not always be ideal if the position of data changes, or if you need to find data based on its content rather than its position. Regular expressions and WHERE conditions serve different purposes, such as searching for patterns or filtering records, rather than directly identifying a specific line by key.