Perl Tutorials - Herong's Tutorial Examples - v6.01, by Dr. Herong Yang
DBM Database Example - English French Dictionary
This section provides a tutorial example of using DBM database files to build an English to French dictionary with insert, update, delete and print functions.
As the first example with DBM files, I wrote several simple programs to create a simple English French dictionary, to update the dictionary, and to look up word in the dictionary.
The first program, DbmInsert.pl, creates the dictionary as a DBM file, and inserts a couple of entries:
#- DbmInsert.pl
#- Copyright (c) HerongYang.com. All Rights Reserved.
#
($name) = @ARGV;
die "Missing DBM name.\n" unless $name;
dbmopen(%map,$name,0666);
$map{'apple'} = 'pomme';
$map{'bible'} = 'bible';
$map{'cloth'} = 'tissu';
$map{'computer'} = 'ordinateur';
$map{'good'} = 'bon';
$map{'milk'} = 'lait';
$map{'price'} = 'prix';
$map{'ten'} = 'dix';
dbmclose(%map);
exit;
The mask code, 0666, is an octal number representing a permission setting to allow every user for reading and writing (rw_rw_rw_). Running this program gives no problem:
herong> dbmInsert.pl dictionary
herong> dir dictionary.*
0 dictionary.dir
1,024 dictionary.pag
The second program, DbmPrint.pl, prints the entire content of the dictionary:
#- DbmPrint.pl
#- Copyright (c) HerongYang.com. All Rights Reserved.
#
($name) = @ARGV;
die "Missing DBM name.\n" unless $name;
dbmopen(%map,$name,0666);
while (($key,$val)=each(%map)) {
print($key, ' = ', $val, "\n");
}
dbmclose(%map);
exit;
No trouble to run this program. Notice that the order of the entries is maintained as the same as they were inserted by the first program:
herong> dbmPrint.pl dictionary apple = pomme bible = bible cloth = tissu computer = ordinateur good = bon milk = lait price = prix ten = dix
The third program, DbmUpdate.pl, deletes an entry, and updates another entry:
#- DbmUpdate.pl
#- Copyright (c) HerongYang.com. All Rights Reserved.
#
($name) = @ARGV;
die "Missing DBM name.\n" unless $name;
dbmopen(%map,$name,0666);
delete($map{'apple'});
$map{'cloth'} = 'vetement';
dbmclose(%map);
exit;
Run this program, and print dictionary again. You will see that the new entry is inserted at the end of the file:
herong> dbmUpdate.pl dictionary herong> dbmprint.pl dictionary bible = bible computer = ordinateur good = bon milk = lait price = prix ten = dix cloth = vetement
The fourth program, DbmLookup.pl, looks up a word from the dictionary:
#- DbmLookup.pl
#- Copyright (c) HerongYang.com. All Rights Reserved.
#
($name, $key) = @ARGV;
die "Missing DBM name.\n" unless $name;
die "Missing key.\n" unless $key;
dbmopen(%map,$name,0666);
if ($map{$key}) {
print($key, ' = ', $map{$key}, "\n");
} else {
print($key, " = (not defined)\n");
}
dbmclose(%map);
exit;
Try it with a couple of words:
herong> dbmlookup.pl dictionary apple apple = (not defined) herong> dbmlookup.pl dictionary milk milk = lait
Table of Contents
Data Types: Values and Variables
Expressions, Operations and Simple Statements
Name Spaces and Perl Module Files
Hard References - Addresses of Memory Objects
Objects (or References) and Classes (or Packages)
Typeglob and Importing Identifiers from Other Packages
String Built-in Functions and Performance
File Handles and Data Input/Output
Open Directories and Read File Names
File System Functions and Operations
dbmopen() - Opening DBM Files with Hash Variables
►DBM Database Example - English French Dictionary
DBM Database Example - Book Records with Multiple Fields
Socket Communication Over the Internet
XML::Simple Module - XML Parser and Generator
SOAP::Lite - SOAP Server-Client Communication Module
Perl Programs as IIS Server CGI Scripts
CGI (Common Gateway Interface)
XML-RPC - Remote Procedure Call with XML and HTTP
RPC::XML - Perl Implementation of XML-RPC
Integrating Perl with Apache Web Server
CGI.pm Module for Building Web Pages
LWP::UserAgent and Web Site Testing
Converting Perl Script to Executable Binary