Ruby字符串 #

一、字符串概述 #

字符串是Ruby中最常用的数据类型之一。Ruby的字符串是可变的，支持多种创建方式和丰富的操作方法。

二、创建字符串 #

2.1 字符串字面量 #

ruby 
s1 = 'Hello'
s2 = "Hello"
s3 = %q{Hello}
s4 = %Q{Hello}
s5 = %(Hello)

multiline = <<~TEXT
  这是一个
  多行字符串
TEXT

heredoc = <<-'END'
  这里可以包含 #{变量} 而不会被插值
END

2.2 单引号 vs 双引号 #

ruby 
name = "Ruby"

'Hello, #{name}'
"Hello, #{name}"

'Line 1\nLine 2'
"Line 1\nLine 2"

'Hello \\ World'
"Hello \\ World"

2.3 字符串方法创建 #

ruby 
String.new
String.new("Hello")
"Hello".dup
"Hello".clone

2.4 Here Document #

ruby 
text = <<~HTML
  <html>
    <head>
      <title>#{title}</title>
    </head>
    <body>
      #{content}
    </body>
  </html>
HTML

code = <<~RUBY
  def hello
    puts "Hello, World!"
  end
RUBY

三、字符串插值 #

3.1 基本插值 #

ruby 
name = "Ruby"
version = 3.3

"Hello, #{name}!"
"Ruby #{version}"
"1 + 2 = #{1 + 2}"
"#{name.upcase} is awesome"

3.2 格式化字符串 #

ruby 
name = "Ruby"
age = 30

sprintf("Name: %s, Age: %d", name, age)
"Name: %s, Age: %d" % [name, age]
format("Name: %s, Age: %d", name, age)

"%.2f" % 3.14159
"%10s" % "Ruby"
"%-10s" % "Ruby"
"%05d" % 42

四、字符串操作 #

4.1 拼接 #

ruby 
"Hello" + " " + "World"
"Hello" " " "World"
"Hello" << " " << "World"
"Hello".concat(" World")
["Hello", "World"].join(" ")

4.2 重复 #

ruby 
"Ruby " * 3
"-" * 20

4.3 索引访问 #

ruby 
s = "Hello, Ruby"

s[0]
s[0, 5]
s[0..4]
s[0...5]
s[-4..-1]
s[/Ruby/]
s[/R(.)/, 1]

4.4 切片 #

ruby 
s = "Hello, World"

s.slice(0, 5)
s.slice(0..4)
s.slice!(-5..-1)

4.5 修改 #

ruby 
s = "Hello"

s[0] = "h"
s[0, 5] = "Hi"
s << " World"
s.prepend("Say: ")
s.insert(5, " there")
s.replace("New string")

五、字符串方法 #

5.1 大小写转换 #

ruby 
s = "Hello Ruby"

s.upcase
s.downcase
s.capitalize
s.swapcase
s.upcase!
s.downcase!

5.2 去除空白 #

ruby 
s = "  Hello  "

s.strip
s.lstrip
s.rstrip
s.strip!
s.squeeze(" ")

5.3 查找 #

ruby 
s = "Hello, Ruby World"

s.include?("Ruby")
s.start_with?("Hello")
s.end_with?("World")
s.index("Ruby")
s.rindex("o")
s =~ /Ruby/
s.match(/Ruby/)
s.match?(/Ruby/)

5.4 替换 #

ruby 
s = "Hello, Ruby"

s.sub("Ruby", "World")
s.gsub("o", "0")
s.sub!(/Ruby/, "World")
s.gsub!(/[aeiou]/, "*")
s.tr("aeiou", "12345")
s.tr_s("a-z", "A-Z")

5.5 分割与连接 #

ruby 
s = "apple,banana,cherry"

s.split(",")
s.split(/,\s*/)
s.split("", 3)

arr = ["apple", "banana", "cherry"]
arr.join(", ")
arr * ", "

5.6 反转与排序 #

ruby 
s = "Ruby"

s.reverse
s.reverse!
s.chars.sort.join

5.7 长度与空判断 #

ruby 
s = "Hello"

s.length
s.size
s.empty?
s.nil?
s.blank?

六、字符串转换 #

6.1 类型转换 #

ruby 
"42".to_i
"3.14".to_f
"1,2,3".to_a
"hello".to_sym
"hello".chars
"hello".lines
"hello".bytes
"hello".codepoints

6.2 字符与ASCII #

ruby 
"A".ord
65.chr
"Hello".bytes
"Hello".chars
"你好".bytes
"你好".chars

6.3 数值与字符串 #

ruby 
42.to_s
42.to_s(16)
42.to_s(2)
3.14.to_s
Rational(1, 3).to_s

七、字符串编码 #

7.1 编码查看与转换 #

ruby 
s = "你好"

s.encoding
s.encode("GBK")
s.force_encoding("GBK")
s.valid_encoding?

7.2 编码列表 #

ruby 
Encoding.list
Encoding.name_list
Encoding.find("UTF-8")
Encoding.default_external
Encoding.default_internal

7.3 编码问题处理 #

ruby 
s = "你好"

begin
  s.encode("ASCII")
rescue Encoding::UndefinedConversionError => e
  puts "编码转换失败: #{e}"
end

s.encode("ASCII", invalid: :replace, undef: :replace)

八、字符串比较 #

8.1 相等比较 #

ruby 
"hello" == "hello"
"hello" === "hello"
"hello".eql?("hello")
"hello".equal?("hello")

8.2 大小比较 #

ruby 
"a" <=> "b"
"apple" <=> "banana"
"Apple" <=> "apple"
"hello" <=> "hello"

8.3 大小写不敏感比较 #

ruby 
"Hello".casecmp("hello")
"Hello".casecmp?("hello")
"Hello".downcase == "hello".downcase

九、正则表达式 #

9.1 匹配 #

ruby 
s = "Hello, Ruby 3.3"

s =~ /Ruby/
s.match(/Ruby/)
s.match?(/Ruby/)
s =~ /(\d+)\.(\d+)/
$1
$2

9.2 捕获 #

ruby 
s = "Ruby 3.3"

match = s.match(/(\w+)\s+(\d+)\.(\d+)/)
match[0]
match[1]
match[2]
match[3]
match.captures
match.names

9.3 替换 #

ruby 
s = "Hello, Ruby"

s.sub(/Ruby/, "World")
s.gsub(/[aeiou]/, "*")
s.sub(/(\w+)/, '<\1>')
s.gsub(/(?<word>\w+)/, '[\k<word>]')

9.4 分割 #

ruby 
"apple, banana; cherry".split(/[,;]\s*/)
"a1b2c3".split(/\d/)

十、实用示例 #

10.1 驼峰转换 #

ruby 
def camel_case(str)
  str.split('_').map(&:capitalize).join
end

def snake_case(str)
  str.gsub(/([A-Z])/, '_\1').downcase.gsub(/^_/, '')
end

camel_case("hello_world")
snake_case("HelloWorld")

10.2 截断字符串 #

ruby 
def truncate(str, length = 100, omission = "...")
  return str if str.length <= length
  str[0, length - omission.length] + omission
end

truncate("这是一段很长的文字，需要截断显示", 10)

10.3 单词统计 #

ruby 
def word_count(str)
  str.split(/\s+/).size
end

def char_count(str, char)
  str.count(char)
end

word_count("Hello, Ruby World")
char_count("Hello", "l")

10.4 字符串模板 #

ruby 
class Template
  def initialize(template)
    @template = template
  end

  def render(binding)
    ERB.new(@template).result(binding)
  end
end

require 'erb'
template = "Hello, <%= name %>! You are <%= age %> years old."
name = "Ruby"
age = 30
ERB.new(template).result(binding)

10.5 密码生成 #

ruby 
def generate_password(length = 12)
  chars = ('a'..'z').to_a + ('A'..'Z').to_a + ('0'..'9').to_a + '!@#$%^&*'.chars
  Array.new(length) { chars.sample }.join
end

generate_password(16)

十一、字符串性能优化 #

11.1 冻结字符串 #

ruby 
STRING = "constant string".freeze

def process
  "literal string".frozen?
end

"literal string".frozen?

11.2 字符串构建 #

ruby 
# 慢
result = ""
1000.times { result += "x" }

# 快
result = String.new
1000.times { result << "x" }

# 更快
result = +""
1000.times { result << "x" }

11.3 使用数组join #

ruby 
# 慢
result = ""
items.each { |item| result += item.to_s }

# 快
items.map(&:to_s).join

十二、总结 #

本章我们学习了：

  1. 创建字符串：单引号、双引号、Here Document
  2. 字符串插值：#{}、sprintf、format
  3. 字符串操作：拼接、切片、修改
  4. 字符串方法：大小写、查找、替换、分割
  5. 字符串编码：UTF-8、GBK转换
  6. 正则表达式：匹配、捕获、替换
  7. 性能优化：freeze、字符串构建

接下来让我们学习Ruby的布尔类型！

最后更新：2026-03-27