ruby的字符型

单行字符串的输出:

str = 'hello the world' p str    #=> "hello the world" puts str    #=> hello the world

多行字符串的输出:

str = <<EOS     This is test.     Ruby, the Object Oriented Script Language. EOS puts str     #=>This is test.           Ruby, the Object Oriented Script Language.

字符串的结合:

str = 'hello' puts str + ' the world'    #=> hello the world

字符串的追加:

str = 'hello' str << ' the world' puts str    #=> hello the world

生成重复的字符串:

str = 'hello ' puts str*3    #=> hello hello hello

大小写字母的变换:

str = 'I Love Ruby' puts str.upcase    #=> I LOVE RUBY puts str.downcase    #=> i love ruby

字符串中的部分字符的取得:

str = "Apple Banana Orange" puts str[0..4]     #=> Apple puts str[6, 6]     #=> Banana

字符串中的部分字符的置换:

str = "Apple Banana Apple Orange" str[0..4] = "Vine"     #=> str = "Vine Banana Apple Orane" str[5, 6] = "Lemon"     #=> str = "Vine Lemon Apple Orange" str.sub("Apple", "Pine")     #=> str = "Pine Banana Apple Orange" str.gsub("Apple", "Pine")     #=> str = "Pine Banana Pine Orange"

字符串中变数的展开:

value = 123 puts "value is #{value}"     #=> value is 123

字符串中方法的展开:

def sub(str)     "Hello, #{str}." end puts "Say #{sub('Tomoya')}"     #=> Say Hello, Tomoya.

削除字符串头和尾的空格:

str = ' Hello, Ruby! ' p s.strip     #=> "Hello, Ruby!"

削除字符串尾部的换行:

str = 'Hello, Ruby!\n' p str.chomp    #=> "Hello, Ruby!" p str.strip    #=> "Hello, Ruby!"

字符型向数值型的转换:

str = '99' i = 1 puts i + str.to_i    #=> 100

数值型向字符型的转换:

str = '99' i = 1 p i.to_s + str    #=> "199"

字符型(数值型)向浮点小数型的转换:

str = '99' puts str.to_f    #=> 99.0

下一个字符串的取得:

p "9".succ    #>= "10" p "a".succ    #>= "b" p "AAA".succ    #>= "AAB" p "A99".succ    #>= "B00" p "A099".succ    #>= "A100"

检查字符串中是否有相同字符出现:

str = "Apple Banana Apple Orange" # 从左则开始查找 puts str.index("Apple")    #=> 0 puts str.index("Banana")    #=> 6 puts str.index("Apple", 6)    #=> 13 # 从右则开始查找 puts str.rindex("Apple")    #=> 13 puts str.rindex("Apple", 6)    #>= 0

字符串的居中,居左和居右:

str = "Ruby" p str.center(10)     #=> " Ruby " p str.ljust(10)    #=> "Ruby " p str.rjust(10)    #=> " Ruby"

字符串的查找

查找匹配字符
用正则表达式查找匹配字符时,使用 =~ 运算符.

# 查找含有全角空格和半角空格. p ([\s\t] =~ 'a c')    #=>  1 p ([\s\t] =~ 'abc')    #=>  nil

查找匹配字符最初出现在位置
查找匹配字符最初出现在位置时,使用 String#index

p 'xxxabcabcabcxxx'.index('abc')    #=>  3 p 'xxxabcabcabcxxx'.index('.')     #=>  nil p 'xxx..............xxx'.index('.')     #=>  3

查找匹配字符最后出现在位置
查找匹配字符最后出现在位置时,使用 String#rindex

p 'xxxabcabcabcxxx'.rindex('abc')    #=>  9 p 'xxxabcabcabcxxx'.rindex('.')     #=>  nil p 'xxx..............xxx'.rindex('.')     #=>  16

取得匹配字符外的字符串
取得到匹配字符之后的字符串,使用 Regexp#match

m = /abc/.match('xxxabcabcabcxxx') p m.post_match    #=>  "abcabcxxx" m = 'xxxabcabcabcxxx'.match(/abc/) p m.post_match    #=>  "abcabcxxx"

查找字符串中匹配的所有字符
查找字符串中匹配的所有字符,使用 String#scan

# 查找字符串中的所有字母. str = "abc所\ndef有\nghi字符\n" str.scan(/[a-z]+/){ |s|     p s } #=>  "abc" #=>  "def" #=>  "ghi"

取得含有匹配字符的一行
含有匹配字符的复数行.使用 String#grep (Enumerble#grep)

# 输出含有字母 a 和 g 的一行. str = "abc所\ndef有\nghi字符\n" str.grep(/[ag]/){ |line|     p line } #=>  "abc所\n" #=>  "ghi字符\n"

以下的两种写法同上相同

str.grep(re){ |line|     # 处理内容 }

str.each{ |line|     if re =~ line         # 处理内容     end }