ruby字符串處理函數

出處：http://blog.163.com/ma95221@126/blog/static/2482210220100159515220/

1.返回字符串的長度
str.length => integer

2.判斷字符串中是否包含另一個串
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,默認分隔符爲空格
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.字符串替換
str.gsub(pattern, replacement) => new_str
str.gsub(pattern) {|match| block } => new_str

"hello".gsub(/[aeiou]/, '*')              #=> "h*ll*"     #將元音替換成*號
   "hello".gsub(/([aeiou])/, '<\1>')         #=> "h<e>ll<o>"   #將元音加上尖括號,\1表示保留原有字符???
   "hello".gsub(/./) {|s| s[0].to_s + ' '}   #=> "104 101 108 108 111 "

 字符串替換二:
str.replace(other_str) => str
   s = "hello"         #=> "hello"
   s.replace "world"   #=> "world"

6.字符串刪除:

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.去掉前和後的空格
str.lstrip => new_str

   " hello ".lstrip   #=> "hello "
   "hello".lstrip       #=> "hello"

8.字符串匹配
str.match(pattern) => matchdata or nil

9.字符串反轉
str.reverse => new_str

"stressed".reverse   #=> "desserts"

10.去掉重複的字符
str.squeeze([other_str]*) => new_str
"yellow moon".squeeze                  #=> "yelow mon" #默認去掉串中所有重複的字符
" now   is the".squeeze(" ")         #=> " now is the" #去掉串中重複的空格
"putters shoot balls".squeeze("m-z")   #=> "puters shot balls" #去掉指定範圍內的重複字符

11.轉化成數字
str.to_i=> str
"12345".to_i             #=> 12345

chomp和chop的區別:
chomp:去掉字符串末尾的\n或\r
chop:去掉字符串末尾的最後一個字符,不管是\n\r還是普通字符

"hello".chomp            #=> "hello"
   "hello\n".chomp          #=> "hello"

   "hello\r\n".chomp        #=> "hello"
   "hello\n\r".chomp        #=> "hello\n"
   "hello\r".chomp          #=> "hello"
   "hello".chomp("llo")     #=> "he"

"string\r\n".chop   #=> "string"
   "string\n\r".chop   #=> "string\n"
   "string\n".chop     #=> "string"
   "string".chop       #=> "strin"