Tutorial Addendum on Perl - Allotment A - Alive with DBM Files

This affiliate describes:

    

    
• How bind a DBM book to a assortment object.
  
      



    
• Sample programs to use DBM files.
  
      



    

Opening DBM Files with Assortment Objects

    

Perl allows us to admission DBM files by bounden them to assortment objects. There are two

    

related functions:

    

1. dbmopen() - A action to bind the defined assortment capricious to the specified

    

DBM file. The defined affectation amount will be acclimated as the permission code,

    

if the defined DBM book does not exist. Of course, ahead absolute entries

    

of the assortment capricious will be removed at the time of binding.

    

    
rc = dbmopen(hash_variable, dbm_name, mask);

    

2. dbmclose() - A action to un-bind the defined assortment capricious from the binded

    

DBM file.

    

    
rc = dbmclose(hash_variable);

    

DBM Archetype - English French Dictionary

    

As the first archetype with DBM files, I wrote several simple programs to create

    

a simple English French dictionary, to amend the dictionary, and to attending up word

    

in the dictionary.

    

The first program, DbmInsert.pl, creates the concordance as a DBM file, and inserts a couple

    

of entries:

    

 

    
#- DbmInsert.pl

    
#- Absorb (c) 1996 by Dr.  Yang

    
#

    
   ($name) = @ARGV;

    
   die "Missing DBM name.

" unless $name;

    
   dbmopen(%map,$name,0666);

    
   $map{ angel } =  pomme ;

    
   $map{ bible } =  bible ;

    
   $map{ bolt } =  tissu ;

    
   $map{ computer } =  ordinateur ;

    
   $map{ acceptable } =  bon ;

    
   $map{ milk } =  lait ;

    
   $map{ amount } =  prix ;

    
   $map{ ten } =  dix ;

    
   dbmclose(%map);

    
   exit;

    

The affectation code, 0666, is an octal amount apery a permission ambience

    

to acquiesce every user for account and autograph (rw_rw_rw_). Active this program

    

gives no problem:

    

 

    
>DbmInsert.pl dictionary

    
>dir dictionary.*

    
    0 dictionary.dir

    
1,024 dictionary.pag

    

The additional program, DbmPrint.pl, prints the absolute agreeable of the dictionary:

    

 

    
#- DbmPrint.pl

    
#- Absorb (c) 1996 by Dr.  Yang

    
#

    
   ($name) = @ARGV;

    
   die "Missing DBM name.

" unless $name;

    
   dbmopen(%map,$name,0666);

    
   while (($key,$val)=each(%map)) {

    
      print($key,   =  , $val, "

");

    
   }

    
   dbmclose(%map);

    
   exit;

    

No agitation to run this program. Apprehension that the adjustment of the entries is maintained

    

as the aforementioned as they were amid by the first program:

    

 

    
>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 addition entry:

    

 

    
#- DbmUpdate.pl

    
#- Absorb (c) 1996 by Dr.  Yang

    
#

    
   ($name) = @ARGV;

    
   die "Missing DBM name.

" unless $name;

    
   dbmopen(%map,$name,0666);

    
   delete($map{ angel });

    
   $map{ bolt } =  vetement ;

    
   dbmclose(%map);

    
   exit;