Slide 7.1: Variable-length record addition demonstrations

Slide 6.11: Storage fragmentation combat
Slide 7.2: Variable-length record addition demonstrations (cont.)
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Variable-Length Record Addition Demos

The following demonstrations show the additions of variable-length records to a book file by using an avail list. The first interface requests users to download a book information file and then select an option to use the system.

Select an Option to Use the System.
URL:	Clear system Download books Help Start processing
Password:

One example of the downloaded file avail.txt is

File Structures: An Object-Oriented Approach with C++|0201874016|94.80|360|
Learning WML & WMLScript|1565929470|17.48|12|
XML in a Nutshell, 2nd Edition|0596002920|39.95|39|
Java and XSLT|0596001436|26.37|890|
WAP Servlets: Developing Dynamic Web Content With Java and WML|047139307|32.99|4|
WAP Development with WML and WMLScript|0672319462|18.99|56|
Advances in Security and Payment Methods for Mobile Commerce|1591403456|89.95|182|
M Commerce: Technologies, Services, and Business Models|0471135852|23.09|5|

where

each record is with a variable length,
each record has four variable-length fields: title, ISBN, price, and quantity,
the character ‘|’ is the field delimiter, and
each record is ended with a newline ‘\n’.

Note that these demonstrations only show variable-length record additions, but not deletions. The file avail.txt will not work for these demonstrations. You may download the file avail1.txt or avail2.txt in the next slide for demonstrations.