Ruby中的String#split方法的用法

如果limit参数被忽略，跟踪空段被抑制，如果limit是个正数，那么至多返回limit个字段（如果是1，那么将整个字符串作为一个字段返回），如果是个负数，那么跟踪空段不被抑制。
" now's the time".split #=> ["now's", "the", "time"]
" now's the time".split(' ') #=> ["now's", "the", "time"]
" now's the time".split(/ /) #=> ["", "now's", "", "the", "time"]
' were specified.
如果pattern被忽略，将用$;来分隔，如果$;没有设置（就是在默认状态），split将制定空格' '
If the _limit_ parameter is omitted, trailing null fields are
suppressed. If _limit_ is a positive number, at most that number of
fields will be returned (if _limit_ is +1+, the entire string is
"1, 2.34,56, 7".split(%r{,\s*}) #=> ["1", "2.34", "56", "7"]
"hello".split(//) #=> ["h", "e", "l", "l", "o"]
还有它和String.scan的区别，split中的pattern是分隔符，而scan中的pattern指的是要匹配的东西。
"123=342=4234=523421=6424".scan(/\d+/) #=> ["123","342","4234","523421","6424"]
"1,2,,3,4,,".split(',') #=> ["1", "2", "", "3", "4"]
"1,2,,3,4,,".split(',', 4) #=> ["1", "2", "", "3,4,,"]
"hello".split(//, 3) #=> ["h", "e", "llo"]
"hi mom".split(%r{\s*}) #=> ["h", "i", "m", "o", "m"]
"mellow yellow".split("ello") #=> ["m", "w y", "w"]
str.split(pattern=$;, [limit]) => anArray
------------------------------------------------------------------------
Divides _str_ into substrings based on a delimiter, returning an
array of these substrings.
将一个字符串用分隔符分割成一些子字符串，并返回一个包含这些子字符串的数组。
If _pattern_ is a +String+, then its contents are used as the
delimiter when splitting _str_. If _pattern_ is a single space,
returned as the only entry in an array). If negative, there is no
limit to the number of fields returned, and trailing null fields
are not suppressed.
Ruby中的String#split方法的用法2007-04-25 08:52
split是String类的一个类方法，我根据ri String.split提供的内容简单翻译一下。
----------------------------------------------------------- String#split
_str_ is split on whitespace, with leading whitespace and runs of
contiguous whitespace characters ignored.
如果pattern部分是一个字符串，那么用它作分割符来分隔，如果pattern是一个空格，那么在空格处分割，并且临近的空格被忽略。
"1,2,,3,4,,".split(',', -4) #=> ["1", "2", "", "3", "4", "", ""]
如果包含特殊字符，注意转义
"wo | shi | yi | ge | bing".split(/\s*\|\s*) #竖杠别忘了转义
If _pattern_ is a +Regexp+, _str_ is divided where the pattern
matches. Whenever the pattern matches a zero-length string, _str_
is split into individual characters.
如果匹配项被括起来，那么则会保留分割符，例如：
"Three little words".split(/\s+/) #===>["three","little",words"]
"Three little words".split(/(\s+)/) #===>["three"," ","little"," ","words"] 保留了空格
如果pattern是个正则表达式，那么在匹配pattern的地方分割，当pattern是长度为0的字符串，那么split将把字符串分割为单个字符
If _pattern_ is omitted, the value of +$;+ is used. If +$;+ is
+nil+ (which is the default), _str_ is split on whitespace as if `