str.lstrip => new_str
" hello ".lstrip #=> "hello "
"hello".lstrip #=> "hello"
8.字符串匹配
str.match(pattern) => matchdata or nil
9.字符串反转
str.reverse => new_str
"stressed".reverse #=> "desserts"
10.去掉重复的字符
str.squeeze([other_str]*) => new_str
"yellow moon".squeeze #=> "yelow mon" #默认去掉串中所有重复的字符
" now is the".squeeze(" ") #=> " now is the" #去掉串中重复的空格
"putters shoot balls".squeeze("m-z") #=> "puters shot balls" #去掉指定范围内的重复字符
11.转化成数字
str.to_i=> str
"12345".to_i #=> 12345
chomp和chop的区别:
chomp:去掉字符串末尾的n或r
chop:去掉字符串末尾的最后一个字符,不管是nr还是普通字符
"hello".chomp #=> "hello"
"hellon".chomp #=> "hello"
"hellorn".chomp #=> "hello"
"hellonr".chomp #=> "hellon"
"hellor".chomp #=> "hello"
"hello".chomp("llo") #=> "he"
"stringrn".chop #=> "string"
"stringnr".chop #=> "stringn"
"stringn".chop #=> "string"
"string".chop #=> "strin"
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.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,
_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。
