October 2022
Beginner to intermediate
390 pages
7h 5m
Chinese
Content preview from Perl语言入门（第8版）
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178
｜
第
9
章
新的大小写转换特性对于
İ
stanbul
之类加点的字符串不起作用。因为其中
I
的
小写版本其实是一个组合了点号的
i
，类似
i
。你可以借助
Unicode::Casing
模
块完成类似的复杂转换操作。
这些大小写转换操作符其实也可以用内置函数
lc
、
uc
、
fc
、
lcfirst
以及
ucfirst
来实
现：
my $start = "Fred";
my $uncapp = lc( $start ); # fred
my $uppered = uc( $uncapp ); # FRED
my $lowered = lc( $uppered ); # fred
my $capped = ucfirst( $lowered ); # Fred
my $folded = fc( $uncapped ); # fred
元字符转义
还有一个类似大小写转换的转义操作。
\Q
会把后续字符串中出现的所有元字符自动转
义为本意字符。比如下面的代码，想把名字前出现的所有左括号字符去除，于是写成
这样：
if ( s/(((Fred/Fred/ ) { #
编译时就会提示错误！
print "Removed parens\n";
}
上面的代码在编译时就会提示错误，所以必须把每个括号转义为字符本身：
if ( s/\(\(\(Fred/Fred/ ) { #
编译通过，但看起来很凌乱！
print "Removed parens\n";
}
简直就是烦人。所有的反斜线把模式的结构拆得支离破碎。借助 ...
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