regular expressions are accessible in most programing languages...used for pattern matching.

DFA and NFA:

Deterministic Finite Automation and Nondeterministic Finite Automation

an art project needs to come out of regular expressions

perl regex operates almost identical to sed

good examples:

Example 1-1. Simple match

# Match Spider-Man, Spiderman, SPIDER-MAN, etc.
my $dailybugle = "Spider-Man Menaces City!";
if ($dailybugle =~ m/spider[- ]?man/i) { do_something(  ); }
Example 1-2. Match, capture group, and qr

# Match dates formatted like MM/DD/YYYY, MM-DD-YY,...
my $date  = "12/30/1969";
my $regex = qr!(\d\d)[-/](\d\d)[-/](\d\d(?:\d\d)?)!;
if ($date =~ m/$regex/) {
  print "Day=  ", $1,
        "Month=", $2,
        "Year= ", $3;
}
Example 1-3. Simple substitution

# Convert <br> to <br /> for XHTML compliance
my $text = "Hello World! <br>";
$text =~ s#<br>#<br />#ig;
Example 1-4. Harder substitution

# urlify - turn URL's into HTML links
$text = "Check the website, http://www.oreilly.com/catalog/repr.";
$text =~ 
    s{
      \b                         # start at word boundary
      (                          # capture to $1
       (https?|telnet|gopher|file|wais|ftp) : 
                                 # resource and colon
       [\w/#~:.?+=&%@!\-] +?     # one or more valid
                                 # characters 
                                 # but take as little as
                                 # possible
      )
      (?=                        # lookahead   
        [.:?\-] *                #  for possible punctuation
        (?: [^\w/#~:.?+=&%@!\-]  #  invalid character
          | $ )                  #  or end of string
      )
     }{<a href="$1">$1</a>}igox;
     
     
     
     JAVA:
        "\\b                         # start at word\n" 
     +  "                            # boundary\n"
     +  "(                           # capture to $1\n"
     +  "(https?|telnet|gopher|file|wais|ftp) : \n"
     +  "                            # resource and colon\n"
     +  "[\\w/\\#~:.?+=&%@!\\-] +?   # one or more valid\n"
     +  "                            # characters\n"
     +  "                            # but take as little\n" 
     +  "                            # as possible\n"
      +  ")\n"                                                               
     +  "(?=                         # lookahead\n"
     +  "[.:?\\-] *                  # for possible punc\n"
     +  "(?: [^\\w/\\#~:.?+=&%@!\\-] # invalid character\n"
     +  "| $ )                       # or end of string\n"  
     +  ")";
     
     
almost all regex in different languages use the same nomenclature

javascript

//Convert <br> to <br /> for XHTML compliance
    String text = "Hello world. <br>";
    
    var pattern = /<br>/ig;

    test.replace(pattern, "<br />");
    
yesssss: sed:

$ echo 12/30/1969' |
 sed 's!\([0-9][0-9]\)/\([0-9][0-9]\)/\([0-9]\{2,4\}\)!\2.\1.\3!g'