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Barcelona.pm Curs1211 sess01

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Barcelona.pm Curs1211 sess01

  1. 1. Barcelona Perl Mongers Curs de Perl 2012-11-10 Dades i Operadors
  2. 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. 3. * Before we start... $ perldoc #!/usr/bin/perl #!/usr/bin/env perl use strict;
  4. 4. Datos y Operadores
  5. 5. Datos Escalares● Strings● Numbers
  6. 6. StringsDatos de texto o binarios, sin significado para elprograma, delimitados tipicamente por comillas sencillas o dobles:
  7. 7. Strings my $world = Mundo;my $escaped = Dan OBannon; my $backslash = ;
  8. 8. Comillas doblesmy $newline = "n";my $tab = "t";my $input = "hellonworld!";my $data = "08029t25";my $data = "08029,"Eixample Esquerra"";my $data = qq{08029,"Eixample Esquerra"};
  9. 9. Interpolaciónmy $hello = "Hola, $world!n";my $hello = qq{Hola, "$world"!n};
  10. 10. Funciones tipicas de cadenalength EXPRsubstr EXPR,OFFSET,LENGTH,REPLACEMENTsubstr EXPR,OFFSET,LENGTHsubstr EXPR,OFFSETindex STR,SUBSTR,POSITIONindex STR,SUBSTR
  11. 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. 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$n = "1234"; # number specified as a string
  13. 13. Hashes, Listas y Arreglos
  14. 14. @ Arreglomy @author;$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 " . $author[-1] . "n";print "There are " . @author . " authorsn";my @num = (0..10);my @a = (@b,@c);
  15. 15. # ++$learn$ perldoc List::Util
  16. 16. % Hashmy %name;$name{Asimov} = Isaac;$name{Bear} = Greg;$name{King} = Stephen;
  17. 17. Funciones tipicas para hasheskeys HASHvalues HASHprint "Authors are ".keys(%name)."n";
  18. 18. Identificadores, variables y su notación
  19. 19. NotaciónLas 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. 20. Para acceder el elemento de un arreglo o hash, se utiliza el sigil escalar: $nombre{$id} = Ann; $nombre[$pos] = Ben;
  21. 21. Es posible acceder múltiples valores al mismotiempo utilizando el sigil de arreglo:@nombre{@keys} = @values;@suspendidos = @nombre[@selected];@authors =("Asimov","Bear","King");@authors = qw(Asimov Bear King);
  22. 22. Variables especiales$ perldoc perlvar$ perldoc English @ARGV @INC %ENV %SIG $@@_ $_
  23. 23. I/O
  24. 24. Consola STDINSTDOUTSTDERR
  25. 25. e.g.print STDERR "This is a debug messagen";
  26. 26. Operadores y su precedencia( y su asociatividad ( y su arity ( y su fixity ) ) )
  27. 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 <><=>=ltgtlegenonassoc ==!=<=>eqnecmp~~ left & left |^ left && left || // nonassoc .. ...right ?: right =+= −= *= etc. left ,=> nonassoc list operators (rightward)rightleftleftnot and or xor
  28. 28. => Atencion!print ( ($foo & 255) + 1, "n"); print ++$foo;
  29. 29. * Operadores * Numericos * String * Logicos * Bitwise * Especiales
  30. 30. * Estructuras de Control if (EXPR) BLOCK if (EXPR) BLOCK else BLOCKif (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. 31. e.g.for(my $i=0; $i<@author; ++$i) { print $i.": ".$author[$i]."n";}
  32. 32. for(0..$#author) { print $_.": ".$author[$_]."n";}
  33. 33. foreach my $i (0..$#author) { print $i.": ".$author[$i]."n";}
  34. 34. for(0..1000000) { print $_,"n";}
  35. 35. while(<$fh>) { ... }
  36. 36. * Modificadores if EXPR unless EXPR while EXPR until EXPR foreach LIST next if /^#/; ...
  37. 37. e.g.print "Value is $valn" if $debug;print $i++ while $i <= 10;
  38. 38. Contexto* Voidfind_chores();* Listamy @all_results = find_chores();my ($single_element) = find_chores();process_list_of_results( find_chores() );my ($self,@args) = @_;* Escalarprint "Hay ".@author." autoresn";print "Hay ".scalar(@author)." autoresn";
  39. 39. # ++$learn$ perldoc -f wantarray
  40. 40. * Numericomy $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. 41. * Cadenamy $a = 2;print "The number is ".$a."n";
  42. 42. * Booleanomy $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 contextmy $stringy_x = . $x; # forces string contextmy $boolean_x = !!$x; # forces boolean context
  43. 43. string contextmy $boolean_x = !!$x; # forces boolean context
  44. 44. string contextmy $boolean_x = !!$x; # forces boolean context

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