PERL两个字符串，不关心大小写

104359176

Perl新的版本可能要废除 $_ ，代码不但是用来运行的，还是给未来的自己看的。

qianyemlf

lc($one) eq lc($two)
lc什么意思？

jason680

回复 12# qianyemlf

$ perldoc -f lc
    lc EXPR
    lc      Returns a lowercased version of EXPR. This is the internal
            function implementing the "\L" escape in double-quoted strings.

            If EXPR is omitted, uses $_.


$ perldoc -f uc
    uc EXPR
    uc      Returns an uppercased version of EXPR. This is the internal
            function implementing the "\U" escape in double-quoted strings. It
            does not attempt to do titlecase mapping on initial letters. See
            "ucfirst" for that.

            If EXPR is omitted, uses $_.

            This function behaves the same way under various pragma, such as
            in a locale, as "lc" does.

seufy88

回复 11# 104359176


    废除$_，那之前的代码是否不兼容阿。

zhlong8

不建议的是 my $_，这是个错误的实践，并不是要废除默认参数的用法。 5.18 文档中

Lexical $_ is now experimental

Since it was introduced in Perl v5.10, it has caused much confusion with no obvious solution:

    Various modules (e.g., List::Util) expect callback routines to use the global $_. use List::Util 'first'; my $_; first { $_ == 1 } @list does not work as one would expect.
    A my $_ declaration earlier in the same file can cause confusing closure warnings.
    The "_" subroutine prototype character allows called subroutines to access your lexical $_, so it is not really private after all.
    Nevertheless, subroutines with a "(@)" prototype and methods cannot access the caller's lexical $_, unless they are written in XS.
    But even XS routines cannot access a lexical $_ declared, not in the calling subroutine, but in an outer scope, iff that subroutine happened not to mention $_ or use any operators that default to $_.

It is our hope that lexical $_ can be rehabilitated, but this may cause changes in its behavior. Please use it with caution until it becomes stable.