正则表达式和字符大小写

Question

好吧，我得到了一个相当简单的（至少看起来很简单）。我有一个多行字符串，我只是在尝试用其他东西替换不同的单词。我来给你展示...

#!/usr/bin/perl -w
use strict;

$_ = "That is my coat.\nCoats are very expensive.";
s/coat/Hat/igm;
print;

输出将是
That is my Hat
Hats are very expensive...

第一行的“帽子”不应大写。有什么技巧可以让大小写符合英文的书写方式吗？谢谢 ：）

Answer 1

看 如何替换字符串并保留其大写小写

欲了解更多详情，请访问 如何在 LHS 上不区分大小写地替换，同时在 RHS 上保留大小写？

Answer 2

您可以使用e修饰符s///这样的伎俩：

s/(coat)/ucfirst($1) eq $1 ? 'Hat' : 'hat'/igme;

Answer 3

有关一个，则应该使用\b（字边界），以仅整个单词相匹配。例如s/hat/coat/将改变That到Tcoat没有前导\b。现在，你的问题。旗/e你可以在正则表达式的替换零件使用Perl代码。这样你就可以写一个Perl函数检查匹配的情况下，然后设置替换的情况下适当地：

my $s = "That is my coat.\nCoats are very expensive.";
$s =~ s/(\bcoat)/&same_case($1, "hat")/igme;
print $s, "\n";

sub same_case {
        my ($match, $replacement) = @_;

        # if match starts with uppercase character, apply ucfirst to replacement
        if($match =~ /^[A-Z]/) {
                return ucfirst($replacement);
        }
        else {
                return $replacement;
        }
}

打印：

That is my hat.
Hats are very expensive.

Answer 4

这可以解决问题：

#!/usr/bin/perl -w

use strict;

sub smartSubstitute {
    my $target = shift;
    my $pattern = shift;
    my $replacement = shift;

    $pattern = ucfirst $pattern;
    $replacement = ucfirst $replacement;

    $target =~ s/$pattern/$replacement/gm;

    $pattern = lcfirst $pattern;
    $replacement = lcfirst $replacement;

    $target =~ s/$pattern/$replacement/gm;

    return $target;
}

my $x = "That is my coat.\nCoats are very expansive.";
my $y = smartSubstitute($x, "coat", "Hat");
print $y, "\n";