string 如何在 Perl 中获取字符串的长度？
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How do I get the length of a string in Perl?
提问by Kip
What is the Perl equivalent of strlen()?
Perl 相当于strlen()什么？
回答by Paul Tomblin
perldoc -f length
length EXPR
length Returns the length in characters of the value of EXPR. If EXPR is
omitted, returns length of $_. Note that this cannot be used on an
entire array or hash to find out how many elements these have. For
that, use "scalar @array" and "scalar keys %hash" respectively.
Note the characters: if the EXPR is in Unicode, you will get the num-
ber of characters, not the number of bytes. To get the length in
bytes, use "do { use bytes; length(EXPR) }", see bytes.
回答by Yanick
Although 'length()' is the correct answer that should be used in any sane code, Abigail's length horrorshould be mentioned, if only for the sake of Perl lore.
尽管 'length()' 是应该在任何理智的代码中使用的正确答案，但应该提到Abigail 的长度恐怖，即使只是为了 Perl 知识。
Basically, the trick consists of using the return value of the catch-all transliteration operator:
基本上，这个技巧包括使用 catch-all 音译运算符的返回值：
print "foo" =~ y===c; # prints 3
y///c replaces all characters with themselves (thanks to the complement option 'c'), and returns the number of character replaced (so, effectively, the length of the string).
y///c 用自己替换所有字符（感谢补码选项 'c'），并返回被替换的字符数（因此，实际上是字符串的长度）。
回答by JDrago
length($string)
回答by RANA DINESH
The length()function:
该length()函数：
$string ='String Name';
$size=length($string);
回答by pslessard
You shouldn't use this, since length($string) is simpler and more readable, but I came across some of these while looking through code and was confused, so in case anyone else does, these also get the length of a string:
您不应该使用它，因为 length($string) 更简单且更具可读性，但是我在查看代码时遇到了其中的一些并且感到困惑，所以万一其他人这样做，这些也会得到字符串的长度：
my $length = map $_, $str =~ /(.)/gs;
my $length = () = $str =~ /(.)/gs;
my $length = split '', $str;
The first two work by using the global flag to match each character in the string, then using the returned list of matches in a scalar context to get the number of characters. The third works similarly by splitting on each character instead of regex-matching and using the resulting list in scalar context
前两个通过使用全局标志来匹配字符串中的每个字符，然后在标量上下文中使用返回的匹配列表来获取字符数。第三个通过拆分每个字符而不是正则表达式匹配并在标量上下文中使用结果列表来类似地工作
回答by sqldoug
Not an answer but an observation: I'm running v5.30.2 built for darwin-2level, and I've noticed that if I don't chompmy input first (as with stdin), then calculate the length, the lengthof a single character is not 1, but 2.
不是答案而是观察：我正在运行为 darwin-2level 构建的 v5.30.2，我注意到如果我不chomp先输入（与标准输入一样），然后计算长度，length单个字符的不是 1，而是 2。
Remember those newlines and other hidden characters that could be a factor.
记住那些可能是一个因素的换行符和其他隐藏字符。
And I would love to find Abigail's post, but alas it seems to have been consumed by the ether.
我很想找到阿比盖尔的帖子，但可惜它似乎已经被以太消耗了。
