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$str = "123abcd456";
@match = $str =~ /\d/g; # 1 2 3 4 5 6
$str = "yes is your answer."; $yes = "yes";
print "match\n" if ( $str =~ m/$yes/ ); # match
print "match\n" if ( $str =~ m'$yes' ); #
open (DICT,"/usr/share/dict/words") or die "Can't open dictionary: $!";
while ( <DICT> ) {
$first_word = $1 if ?(^aba.*)?;
$last_word = $1 if /(^aba.*)/;
}
print "$first_word\n"; # aback
print "$last_word\n"; # abating
$text = "3 2 1 wow!";
# use /gc to remember position
while ( $text =~ /(\d)/gc ){ print "$1...\n"; }
# use \G to match rest of text
if ( $text =~ /\G\s*(.+)$/ ) { print $1, "!\n"; }
# 3...
# 2...
# 1...
# wow!
$text = "proton";
while ( $text =~ /(..)/g ) { print "[$1]"; }
# [pr][ot][on]
while ( $text =~ /(?=(..))/g ) { print "[$1]"; }
# [pr][ro][ot][to][on]
$string = "one=1 two=2 three=3";
%hash = $string =~ m/(\w+)=(\w+)/g;
s operator
--------------------------------------------------------------------------------
$pop = "12398712376";
$pop =~ s/(?<=\d)(?=(?:\d{3})+$)/,/;
print "$pop\n";
# 12,398712376
$pop = "12398712376";
$pop =~ s/(?<=\d)(?=(?:\d{3})+$)/,/g;
print "$pop\n";
# 12,398,712,376
$pop = "12398712376";
$pop =~ s/(\d)(\d{3})/$1,$2/g;
print "$pop\n";
# 1,2398,712376
$pop = "12398712376 345345345";
while ( $pop =~ s/(\d)(\d{3})\b/$1,$2/ ){ print "$pop\n"; }
# 12398712,376 345345345
# 12398,712,376 345345345
# 12,398,712,376 345345345
# 12,398,712,376 345345,345
# 12,398,712,376 345,345,345
$pop = "12398712376 345345345";
while ( $pop =~ s/(\d)(\d{3})\b/$1,$2/g ){ print "$pop\n"; }
# 12398712,376 345345,345
# 12398,712,376 345,345,345
# 12,398,712,376 345,345,345
$a = 123;
$a =~ s/2/2*4/e;
# 183
$b = 123; $c = 2*2;
$b =~ s/2/" $c*2 "/e;
# 1 4*2 3
$b = 123; $c = 2*2;
$b =~ s/2/" $c*2 "/ee;
# 183
$string = "anatoliy";
$string =~ s/(\w)/uc($1)/ge;
# ANATOLIY
$str = "1.Smith\n\tJey\n\tAn\n2.Shevchenko\n\tTaras\n";
while ( $str =~ /(^\d.*$)/gm ) {
print "$1\n";
}
# 1.Smith
# 2.Shevchenko
$_ = "1\n2\n9";
$_ =~ s/./+/g;
# +
# +
# +
$_ =~ s/./+/sg;
# +++++
$str = "aBcDe";
$num = $str =~ s/([a-z])/uc($1)/eg;
print "\$str: $str\n"; # $str: ABCDE
print "\$num: $num\n"; # $num: 3
$str = "aBcDe";
($num = $str) =~ s/([a-z])/uc($1)/eg;
print "\$str: $str\n"; # $str: aBcDe
print "\$num: $num\n"; # $num: ABCDE
# put commas in the right places an integer ( from "Camel Book" ).
$_ = "2343454567";
1 while s/(\d)(\d{3})(?!\d)/$1,$2/;
print "$_\n"; # 2,343,454,567
# expand tabs to 8-column spacing ( from "Camel Book" ).
$_ = "abc\t\t\tABC\t3";
1 while s/\t+/'.' x (length($&)*8 - length($`)%8)/e;
print "$_\n";
# abc.....................ABC.....3
# remove nested remarks ( from "Camel Book" ).
$_ = "abc (123(second) ( third )) the end";
1 while s/\([^()]*\)//g;
print "$_\n"; # abc the end
tr operator
--------------------------------------------------------------------------------
$str = "Hello World!";
$str =~ tr/a-z/./; # H.... W....!
$str = "Hello World!";
$str =~ tr/a-z//d; # H W!
$str = "Hello World!";
$str =~ tr/a-z//cd; # elloorld
$str = "Hello World!";
$str =~ tr/a-z/./c; # .ello..orld.
$str = "Heellooo WWoorld!!";
$str =~ tr/a-z//s; # Helo WWorld!!
qr operator
--------------------------------------------------------------------------------
my $np;
$np = qr{\((?:(?>[^()]+)|(??{$np}))*\)}x;
my $funpat = qr/\w+$np/;
my $s = 'my_function_call(1,(2*(3+4)),5)';
if ( $s =~ /^$funpat$/ ){ print "match\n"; }
# match
$palindrom = qr/^ (.+) .? (??{quotemeta reverse $1}) $/xi;
print "Pattern: $palindrom\n";
for ( qw(abcba a bddb abvcba), "" ){
print "",
(($_ !~ /$palindrom/) ? "NOT " : "") . "MATCH => $_\n";
}
# Pattern: (?ix-sm:^ (.+) .? (??{quotemeta reverse $1}) $)
# MATCH => abcba
# NOT MATCH => a
# MATCH => bddb
# NOT MATCH => abvcba
# NOT MATCH =>
# match nested parentheses
my $p;
$p = qr{(?: ({) | (<)) (?:(?>(?(1)[^{}]+|(?(2)[^<>]+)))|
(??{$p}))*
( ?(1)} | (?(2)>) )
}x;
my $mp = qr/m$p/;
my $s = "test m> the end";
if ( $s =~ /$mp/ ){ $s =~ s/$mp/MATCH/; print "$s\n";}
# test MATCH the end
split operator
--------------------------------------------------------------------------------
# "Mastering Regular Expressions", 2nd edition, ch7.
my $text = "IO.SYS:22558:95-10-03:s-sh:optinal";
print qq('$_', ) for ( split(/:/=>$text) );
# 'IO.SYS', '22558', '95-10-03', 's-sh', 'optinal',
print qq('$_\', ) for ( split(/:/ ,$text, 3) );
# 'IO.SYS', '22558', '95-10-03:s-sh:optinal',
my ($x,$y,$z) = split (/:/=>$text);
print "( \$x=$x, \$y=$y, \$z=$z )\n";
# ( $x=IO.SYS, $y=22558, $z=95-10-03 )
my @Paragraphs = split(m/\s*\s*/i => $html); # by paragraphs
my @Lines = split(m/^/m => $lines); # logic lines
print qq(' $_', ) for ( split(// => " a short test ") );
# ' ', ' ', 'a', ' ', 's', 'h', 'o', 'r', 't', ' ', ' ', 't', 'e', 's', 't', ' ', ' ',
print qq('$_', ) for ( split(' ' => " a short test ") );
# 'a', 'short', 'test',
print qq('$_', ) for ( split(/\s+/=> " a short test ") ); # to save beginning
# '', 'a', 'short', 'test',
print qq('$_', ) for ( split(/ / => " a short test ",-1) ); # !!
# '', '', 'a', 'short', '', 'test', '', '',
print qq('$_', ) for ( split(/s+/ => " a short test ") ); # !!
# ' a ', 'hort te', 't ',
print qq('$_', ) for ( split(/(\s)+/=> " a short test ") );
# '', ' ', 'a', ' ', 'short', ' ', 'test', ' ',
print qq('$_', ) for ( split(/(\s+)/=> " a short test ") );
# '', ' ', 'a', ' ', 'short', ' ', 'test', ' ',
print qq('$_', ) for ( split(/( )/ => " a short test ") );
# '', ' ', '', ' ', 'a', ' ', 'short', ' ', '', ' ', 'test', ' ', '', '
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