1 单独处理字符串的字符
如果处理的是ASCII码的文档使用string#each_byte
注意 没有 string#each方法，String#each_byte 速度比 String#scan快 ，String#scan用于配合正则表达式时使用
'foobar'.each_byte { |x| puts "#{x} = #{x.chr}" }
# 102 = f
# 111 = o
# 111 = o
# 98 = b
# 97 = a
# 114 = r
'foobar'.scan( /./ ) { |c| puts c }
# f
# o
# o
# b
# a
# r
2 分割一段文本。并对每个单词进行处理
class String
def word_count
frequencies = Hash.new(0)
downcase.scan(/\w+/) { |word| frequencies[word] += 1 }
frequencies
end
end
p %{Dogs dogs dog dog dogs.}.word_count
3 字符串大小写转换
s = 'HELLO, I am not here , I WENT to tHe MaRKEt' p s.upcase # "HELLO, I AM NOT HERE , I WENT TO THE MARKET"
p s.downcase # "hello, i am not here , i went to the market"
p s.swapcase # "hello, i AM NOT HERE , i went TO ThE mArkeT"
p s.capitalize # "Hello, i am not here , i went to the market"
s = "abc"
p s.tr('a','A')
4处理空白字符
移除开头和结尾空白字符
" \tWhitespace at beginning and end. \t\n\n".strip
# => "Whitespace at beginning and end."
移除一端的空格
s = "
Whitespace madness! "
s.lstrip
# => "Whitespace madness! "
s.rstrip
# => "
Whitespace madness!"
5 判断一个对象可否作为字符串
判断对象是否有to_str方法
'A string'.respond_to? :to_str # => true
Exception.new.respond_to? :to_str # => true
4.respond_to? :to_str # => false