Regular expressions can be used to break up strings. This is what split does. The join function on the other hand takes a list of strings and combines them together again.

$line="Bart  Lisa Maggie Marge Homer";
@simpsons=split(/\s/, $line); #splits $line and uses a piece of whites
+pace as a delimiter.

#@simpsons now contains ("Bart","","Lisa","Maggie","Marge","Homer");
#notice there is an extra space between Bart and Lisa so we get an emp
+ty element in the array there.
#lets try a better delimiter that will eliminate that from happening

@simpsons=split(/\s+/ $line); #now splits $line on 1 or more whitespac
+e characters
#@simpsons now containts ("Bart","Lisa","Maggie","Marge","Homer");
[download]

Suppose we had a list of records of the form
Name|Phone Number|Address
We could open a file while which contained those records and do something like this:

open FILE, "data.txt";
while(<FILE>)
   chomp;
   ($name,$phone,$address)=split(/\|/); #splits the default variable $
+_ on |
                                        #notice we have to put \| sinc
+e | is a metacharacter
                                        #that represents or. Otherwise
+ we'd be matching
                                        #empty string or empty string
                                        #then we place the results in 
+variables instead of a list
                                        #the parentheses around the va
+riable names need
                                        #to be there for this to work 
+properly
   print "Name: $name\n";               #Now we print out the informat
+ion in a more readable form
   print "Phone Number: $phone\n";
   print "Address: $address\n\n";
}
close FILE;
[download]

The function join can be used to reconstruct split up values into one string again. The syntax for calling this function is join($glue, @array) or join($glue,$var1,$var2....) The glue is simply the string that goes between two strings to hold them together. Here are a few examples:

$string=join(" ",@simpsons);
  #string now equals "Bart Lisa Maggie Marge Homer";
$name="Bob";
$phone="555-5555";
$address="42 Tulip Lane, Holland MI, 49423";
$string=join("|",$name,$phone,$address);
#$string is now equal to "Bob|555-5555|42 Tulip Lane, Holland MI, 4942
+3"
[download]