ruby str操作

length函数，返回integer

test_str="test string"

test_str.length =>return 11  (返回字符串长度11)

操作实例

1.9.3-p551 :033 > test_str="test string"
 => "test string"
1.9.3-p551 :034 > test_str.length
 => 11
include? 函数，表示字符串是否包含另外一个字符串，返回boolean

test_str="test string"

test_str.include? "st" => return true

操作实例

1.9.3-p551 :035 > test_str.include? "st"
 => true
1.9.3-p551 :036 > test_str.include?"st"
 => true

1.9.3-p551 :038 > test_str.include?" ing" #（因ing前面有空格所以返回false）
 => false

insert函数，表示字符串插入，返回新的字符串

test_str="test string"

test_str.insert（0，"aaa"） => return "aaatest_string"

操作实例

1.9.3-p551 :049 > test_str
 => "test string"
1.9.3-p551 :050 > puts test_str
test string
 => nil
1.9.3-p551 :051 > test_str.insert(0,"aaa")
 => "aaatest string"
1.9.3-p551 :052 > test_str.insert(0,"aaa")
 => "aaaaaatest string"
1.9.3-p551 :053 > test_str.insert(-1,"aaa")
 => "aaaaaatest stringaaa"

split 字符串分割，默认分隔符为空格

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

操作实例

 1.9.3-p551 :055 > test_str.split().class
 => Array
1.9.3-p551 :056 > test_str.split(/a/)
 => ["", "", "", "", "", "", "test string"]
1.9.3-p551 :057 > test_str.split(//)
 => ["a", "a", "a", "a", "a", "a", "t", "e", "s", "t", " ", "s", "t", "r", "i", "n", "g", "a", "a", "a"]
1.9.3-p551 :058 >
----------------------------------------------------------------

copy

" 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,,"]
-----------------------------------------------------------------

gsub函数 表示字符串替换 返回新的字符串
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???

操作实例
替换：
1.9.3-p551 :023 > a = "caofengzhen"
 => "caofengzhen"
1.9.3-p551 :024 > a.gsub("en","an")
 => "caofangzhan"
1.9.3-p551 :025 > a
 => "caofengzhen"
1.9.3-p551 :026 > a.gsub!("en","an")
 => "caofangzhan"
1.9.3-p551 :027 > a
 => "caofangzhan"
1.9.3-p551 :028 > a.gsub!(/an/,"en")
 => "caofengzhen"
1.9.3-p551 :029 > a
 => "caofengzhen"
匹配次数
1.9.3-p551 :030 >a ="caofengzhen caofengzhen caofengzhen"
1.9.3-p551 :034 > a.gsub("en") {|a| puts a}
en
en
en
en
en
en
 => "caofgzh caofgzh caofgzh"
1.9.3-p551 :035 > a.gsub("en") {|c| puts a}
caofengzhen caofengzhen caofengzhen
caofengzhen caofengzhen caofengzhen
caofengzhen caofengzhen caofengzhen
caofengzhen caofengzhen caofengzhen
caofengzhen caofengzhen caofengzhen
caofengzhen caofengzhen caofengzhen
 => "caofgzh caofgzh caofgzh"

delete函数 表示字符串删除
str.delete([other_str]+) => new_str

操作实例
1.9.3-p551 :059 > a.delete "ca"
 => "ofgzh"
1.9.3-p551 :060 > a.delete "ca","zh"
 => "caofgzh"
1.9.3-p551 :061 > a.delete "ca","gz"
 => "caofgzh"
1.9.3-p551 :062 > "hello".delete "l","lo"
 => "heo"
1.9.3-p551 :063 > "hello".delete "l"
 => "heo"
1.9.3-p551 :064 > "hello".delete "aeiou", "^e"
 => "hell"
1.9.3-p551 :065 > "hello".delete "aeiou"
 => "hll"
1.9.3-p551 :066 > "hello".delete "aeioul"
 => "h"
1.9.3-p551 :067 > "hello".delete "haeioul"
 => ""
1.9.3-p551 :068 >

strip、lstrip、rstrip函数，去掉左右空格、左边空格、右边空格
str.lstrip => new_str
操作实例
1.9.3-p551 :001 > "  caofengzhen   ".strip()
 => "caofengzhen"
1.9.3-p551 :002 > "  caofengzhen   ".lstrip()
 => "caofengzhen   "
1.9.3-p551 :003 > "  caofengzhen   ".rstrip()
 => "  caofengzhen"
1.9.3-p551 :004 >

match函数 字符串匹配
str.match(pattern) => matchdata or nil
操作实例
1.9.3-p551 :016 > " caofengzhen ".match("en")
 => #<MatchData "en">
1.9.3-p551 :017 > " caofengzhen ".match("en")
 => #<MatchData "en">
1.9.3-p551 :018 > " caofengzhen ".match("en")
 => #<MatchData "en">

reverse函数 字符串反转
str.reverse => new_str

操作实例

1.9.3-p551 :022 > " caofengzhen ".reverse
 => " nehzgnefoac "
1.9.3-p551 :023 > " caofengzhen ".reverse()
 => " nehzgnefoac "

to_i\to_s 字符串数字转化

操作实例
1.9.3-p551 :028 > "123A".to_i
 => 123
1.9.3-p551 :029 > "123A4".to_i
 => 123
1.9.3-p551 :030 > "123".to_i
 => 123
1.9.3-p551 :031 > 123.to_s
 => "123"

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\n\r还是普通字符

"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"


字符串运算操作：
"abc" +"def" => "abcdef"
start_with？函数，表示以"str"开头，返回boolean
end_with? 函数，表示以"str"结尾，返回boolean
操作实例
1.9.3-p551 :032 > "caofengfengzhen".end_with?"en"
 => true
1.9.3-p551 :033 > "caofengfengzhen".start_with?"cao"
 => true
1.9.3-p551 :034 > "caofengfengzhen".start_with?"co"
 => false