kk Blog —— 通用基础

str.length => integer

str.index(substring [, offset])   => fixnum or nil
str.index(fixnum [, offset])      => fixnum or nil
str.index(regexp [, offset])      => fixnum or nil

Returns the index of the first occurrence of the given substring, character (fixnum), 
or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, 
it specifies the position in the string to begin the search.

   "hello".index('e')             #=> 1
   "hello".index('lo')            #=> 3
   "hello".index('a')             #=> nil
   "hello".index(101)             #=> 1
   "hello".index(/[aeiou]/, -3)   #=> 4

str.rindex(substring [, fixnum])   => fixnum or nil
str.rindex(fixnum [, fixnum])   => fixnum or nil
str.rindex(regexp [, fixnum])   => fixnum or nil

Returns the index of the last occurrence of the given substring, character (fixnum), 
or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, 
it specifies the position in the string to end the search---characters beyond this point will not be considered.

   "hello".rindex('e')             #=> 1
   "hello".rindex('l')             #=> 3
   "hello".rindex('a')             #=> nil
   "hello".rindex(101)             #=> 1
   "hello".rindex(/[aeiou]/, -2)   #=> 1

str.include? other_str => true or false
"hello".include? "lo"   #=> true
"hello".include? "ol"   #=> false
"hello".include? ?h     #=> true

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"

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,,"]

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 "

str.replace(other_str) => str
s = "hello"         #=> "hello"
s.replace "world"   #=> "world"

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"

str.lstrip => new_str
" hello ".lstrip   #=> "hello "
"hello".lstrip       #=> "hello"

str.match(pattern) => matchdata or nil

str.reverse => new_str
"stressed".reverse   #=> "desserts"

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

str.to_i=> str
"12345".to_i             #=> 12345