1. Barcelona Perl Mongers
Curs de Perl
2012-11-10
Dades i Operadors

2. Dades I Operadors
● tipus bàsics: $scalar @array %hash
● cadenes de caràcters
● operadors numèrics i de cadenes
● control del flux: condicionals, bucles i errors
● entrada/sortida: STDIN STDOUT

3. * Before we start...
$ perldoc
#!/usr/bin/perl
#!/usr/bin/env perl
use strict;

4. Datos y Operadores

5. Datos Escalares
● Strings
● Numbers

6. Strings
Datos de texto o binarios, sin significado para el
programa, delimitados tipicamente por comillas
sencillas o dobles:

7. Strings
my $world = 'Mundo';
my $escaped = 'Dan O'Bannon';
my $backslash = '';

8. Comillas dobles
my $newline = "n";
my $tab = "t";
my $input = "hellonworld!";
my $data = "08029t25";
my $data = "08029,"Eixample Esquerra"";
my $data = qq{08029,"Eixample Esquerra"};

9. Interpolación
my $hello = "Hola, $world!n";
my $hello = qq{Hola, "$world"!n};

10. Funciones tipicas de cadena
length EXPR
substr EXPR,OFFSET,LENGTH,REPLACEMENT
substr EXPR,OFFSET,LENGTH
substr EXPR,OFFSET
index STR,SUBSTR,POSITION
index STR,SUBSTR

11. Functions for SCALARs or strings
"chomp", "chop", "chr", "crypt", "hex", "index","lc",
"lcfirst","length", "oct", "ord", "pack", "q//",
"qq//","reverse", "rindex","sprintf", "substr", "tr///",
"uc", "ucfirst", "y///"
=> Mas cuando hablemos de expresiones
regulares

12. Números
perldoc perlnumber:
$n = 1234; # decimal integer
$n = 0b1110011; # binary integer
$n = 01234; # *octal* integer
$n = 0x1234; # hexadecimal integer
$n = 12.34e−56; # exponential notation
$n = "−12.34e56"; # number specified as a string
$n = "1234"; # number specified as a string

13. Hashes, Listas y Arreglos

14. @ Arreglo
my @author;
$author[0] = 'Asimov';
$author[1] = 'Bear';
$author[2] = 'King';
print "First author is " . $author[0] . "n";
print "Last author is " . $author[$#author] . "n";
print "Last author is " . $author[-1] . "n";
print "There are " . @author . " authorsn";
my @num = (0..10);
my @a = (@b,@c);

15. # ++$learn
$ perldoc List::Util

16. % Hash
my %name;
$name{'Asimov'} = 'Isaac';
$name{'Bear'} = 'Greg';
$name{'King'} = 'Stephen';

17. Funciones tipicas para hashes
keys HASH
values HASH
print "Authors are ".keys(%name)."n";

18. Identificadores, variables y su
notación

19. Notación
Las variables son precedidas de un sigil que
indica el tipo de valor de la variable:
$ Escalar
@ Arreglo
% Hash
e.g.
my($nombre, @nombre, %nombre);

20. Para acceder el elemento de un arreglo o hash,
se utiliza el sigil escalar:
$nombre{$id} = 'Ann';
$nombre[$pos] = 'Ben';

21. Es posible acceder múltiples valores al mismo
tiempo utilizando el sigil de arreglo:
@nombre{@keys} = @values;
@suspendidos = @nombre[@selected];
@authors =("Asimov","Bear","King");
@authors = qw(Asimov Bear King);

22. Variables especiales
$ perldoc perlvar
$ perldoc English
@ARGV
@INC
%ENV
%SIG
$@
@_ $_

23. I/O

24. Consola
STDIN
STDOUT
STDERR

25. e.g.
print STDERR "This is a debug messagen";

26. Operadores y su precedencia
( y su asociatividad ( y su arity ( y su fixity ) ) )

27. $ perldoc perlop
left terms and list operators (leftward)
left −>
nonassoc ++ −−
right **
right !~ and unary + and − left =~ !~ left */%x left +−.
left << >> nonassoc named unary operators nonassoc <><=>=ltgtlege
nonassoc ==!=<=>eqnecmp~~ left & left |^ left && left || // nonassoc .. ...
right ?: right =+= −= *= etc. left ,=> nonassoc list operators (rightward)
right
left
left
not and or xor

28. => Atencion!
print ( ($foo & 255) + 1, "n");
print ++$foo;

29. * Operadores
* Numericos
* String
* Logicos
* Bitwise
* Especiales

30. * Estructuras de Control
if (EXPR) BLOCK
if (EXPR) BLOCK else BLOCK
if (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK
LABEL while (EXPR) BLOCK
LABEL while (EXPR) BLOCK continue BLOCK
LABEL until (EXPR) BLOCK
LABEL until (EXPR) BLOCK continue BLOCK
LABEL for (EXPR; EXPR; EXPR) BLOCK
LABEL foreach VAR (LIST) BLOCK
LABEL foreach VAR (LIST) BLOCK continue BLOCK
LABEL BLOCK continue BLOCK

31. e.g.
for(my $i=0; $i<@author; ++$i) {
print $i.": ".$author[$i]."n";
}

32. for(0..$#author) {
print $_.": ".$author[$_]."n";
}

33. foreach my $i (0..$#author) {
print $i.": ".$author[$i]."n";
}

34. for(0..1000000) {
print $_,"n";
}

35. while(<$fh>) {
...
}

36. * Modificadores
if EXPR
unless EXPR
while EXPR
until EXPR
foreach LIST
next if /^#/;
...

37. e.g.
print "Value is $valn" if $debug;
print $i++ while $i <= 10;

38. Contexto
* Void
find_chores();
* Lista
my @all_results = find_chores();
my ($single_element) = find_chores();
process_list_of_results( find_chores() );
my ($self,@args) = @_;
* Escalar
print "Hay ".@author." autoresn";
print "Hay ".scalar(@author)." autoresn";

39. # ++$learn
$ perldoc -f wantarray

40. * Numerico
my $a = "a";
my $b = "b";
print "a is equal to b " if ($a==$b); # Really?
print "a is equal to b " if ($a eq $b);

41. * Cadena
my $a = 2;
print "The number is ".$a."n";

42. * Booleano
my $a = 0;
print "a is truen" if $a;
$a = 1;
print "a is truen" if $a;
$a = "a";
print "a is truen" if $a;
my $numeric_x = 0 + $x; # forces numeric context
my $stringy_x = '' . $x; # forces string context
my $boolean_x = !!$x; # forces boolean context

43. string context
my $boolean_x = !!$x; # forces boolean context

44. string context
my $boolean_x = !!$x; # forces boolean context