Perl Language(IV)Regular and Control

最新推荐文章于 2020-12-09 19:31:50 发布

magic_dreamer

最新推荐文章于 2020-12-09 19:31:50 发布

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分类专栏： Scripts 文章标签： Perl OO Apache F#

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本文深入探讨Perl语言中的正则表达式应用，包括匹配、比较及替换等操作，并通过实例展示如何使用Perl进行字符串处理。同时介绍了流程控制语句如last、redo和next的应用场景。

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Perl Language(IV)Regular and Control

7. Regular statement(regex)
$string =~ m/$patten/
$string =~ m{$patten}
$string =~ m|$patten|
$string =~ m!$patten!
$string =~ /$patten/

my $answer = "monger";
until ((my $patten = <STDIN>) =~ /$answer/) {
print "wrong\n";
};

my $answer = "mo*r";
while (1) {
if ((my $patten = <STDIN>) =~ /$answer/) {
print "*match*\n";
} else {
print "*not match*\n";
}
};

my $answer = "mo{2,4}r";

my $answer = "(wow)+";

8. More Regex
/f(oo|ee)t/ # foot or feet
/on (March|April|May)/

$content =~ /[pP]erl/;

$content =~ /perl/i; # charactor 'i' is for ignore the Capital letter

my $content = "I like perl I am a perl monger";
if ($content =~/I like(.*)monger/) {
print "*$1*\n";
}

We can get all the charactors between 'like' and 'monger'

8.7. Compare and Replace
my $content = "I love Java";
print $content if ($content =~ s/java/perl/i);

console output:
I love perl

s is for replacing. i is for ignoring the Capital charactors.

my $content = "I love Perl. I am a perl monger";
print $content if ($content =~ s/perl/Perl/gi);

console output:
I love Perl. I am a Perl monger

g is for all.

8.8. Replacing in our own string
my $string = "123456";
print $string if ($string =~ s/(1)(2)(3)(4)(.*)/$3$2$1$4$5/);

console output:
321456

9. Flow Control
9.1.1 last
break the loop.

for (1...10) {
last if ($_ == 8);
print $_;
}

console output:
1234567

9.1.2 redo
redo the things in loop
for (1...10) {
$_++;
redo if ($_ == 8);
print $_ . " ";
}

console output:
2 3 4 5 6 7 9 9 10 11

9.1.3 next
omit the current loop
for (1...10) {
next if ($_%2);
print $_ . " ";
}

console output:
2 4 6 8 10

references:
http://easun.org/perl/perl-toc/
http://perl.apache.org/