1.返回字符串的长度

str.length => integer

2.判断字符串中是否包含另一个串

str.include? other_str => true or false

"hello".include? "lo"   #=> true

"hello".include? "ol"   #=> false

"hello".include? ?h     #=> true

3.字符串插入

str.insert(index, other_str) => str

"abcd".insert(0, 'X')    #=> "Xabcd"

"abcd".insert(3, 'X')    #=> "abcXd"

"abcd".insert(4, 'X')    #=> "abcdX"

"abcd".insert(-3, 'X')

-3, 'X')   #=> "abXcd"

"abcd".insert(-1, 'X')   #=> "abcdX"

4.字符串分隔,默认分隔符为空格

str.split(pattern=$;, [limit]) => anArray

" now's the time".split        #=> ["now's", "the", "time"]

"1, 2.34,56, 7".split(%r{,s*}) #=> ["1", "2.34", "56", "7"]

"hello".split(//)               #=> ["h", "e", "l", "l", "o"]

"hello".split(//, 3)            #=> ["h", "e", "llo"]

"hi mom".split(%r{s*})         #=> ["h", "i", "m", "o", "m"]

"mellow yellow".split("ello")   #=> ["m", "w y", "w"]

"1,2,,3,4,,".split(',')         #=> ["1", "2", "", "3", "4"]

"1,2,,3,4,,".split(',', 4)      #=> ["1", "2", "", "3,4,,"]

5.字符串替换

str.gsub(pattern, replacement) => new_str

str.gsub(pattern) {|match| block } => new_str

"hello".gsub(/[aeiou]/, '*')              #=> "h*ll*"     #将元音替换成*号

"hello".gsub(/([aeiou])/, '<1>')         #=> "h<e>ll<o>"   #将元音加上尖括号,1表示保留原有字符???

"hello".gsub(/./) {|s| s[0].to_s + ' '}   #=> "104 101 108 108 111 "

字符串替换二:

str.replace(other_str) => str

s = "hello"         #=> "hello"

s.replace "world"   #=> "world"

6.字符串删除

str.delete([other_str]+) => new_str

"hello".delete "l","lo"        #=> "heo"

"hello".delete "lo"            #=> "he"

"hello".delete "aeiou", "^e"   #=> "hell"

"hello".delete "ej-m"          #=> "ho"

7.去掉前和后的空格

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"

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