Manipulating Data with Reference Modification and STRING

You can manipulate data items in detail in two ways:

• The STRING statement. This statement concatenates the partial or complete contents of two or more data items and stores the result.

  In general, using STRING is easier to read and implement. However, it can be resource-intensive, particularly if used many times in a program. You can use STRING in programs that do not incur a lot of overhead for other reasons, such as significant file I/O.

• Reference modification. This technique enables you to make references to (and change) parts of a data item by starting values, for a specified length.

  Reference modification is more efficient, but can lead to code that is more difficult to read and maintain. It is a way to improve performance in programs that use STRING heavily and are running slowly or growing too large.

For example, the following two statements are equivalent. In both examples, street-address is 25 bytes long:

STRING street-address DELIMITED BY SIZE INTO print-rec 
    WITH POINTER num-char
MOVE street-address TO print-rec (num-char: 25)