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/Perl|Python/

/P(erl|ython)/

/\d\d:\d\d:\d\d/ # a time such as 12:34:56
/Perl.*Python/  # Perl, zero or more other chars, then Python
/Perl Python/  # Perl, a space, and Python
/Perl *Python/  # Perl, zero or more spaces, and Python
/Perl +Python/  # Perl, one or more spaces, and Python
/Perl\s+Python/ # Perl, whitespace characters, then Python
/Ruby (Perl|Python)/ # Ruby, a space, and either Perl or Python

puts "Scripting language mentioned: #{line}" if line =~ /Perl|Python/

line.gsub(/Perl|Python/, 'Ruby')

phone = "139-1234-5678"
if phone =~ /(\d{3})-(\d{4})-(\d{4})/
 start_with = $1
 mid_num = $2
 end_as = $3
end

puts "I can say my name" =~ /name/ #-> 13

a = /name/.match("I can say my name, my name I can say") #-> a is MatchData
puts a[0] #-> name

b1=/[A-Za-z]+,[A-Za-z]+,Mrs"Jack,Wang,Mrs., nice person")
puts b1[0] #-> Jack,Wang,Mrs

b2=/(([A-Za-z]+),([A-Za-z]+)),Mrs"Jack,Wang,Mrs., nice person:)
puts b2[0] #-> Jack,Wang,Mrs
puts b2[1] #-> Jack,Wang
puts b2[2] #-> Jack
puts b2[3] #-> Wang

teststr="abcd!efg!"
match=/.+!/.match(teststr)
puts match[0] #-> abcd!efg!

limitmatch=/.+"htmlcode">

c=/\b\w+\b/.match("!!Stephen**")

puts c[0] #-> Stephen




前视断言
前视断言表示想要知道下一个指定的是什么，但并不匹配
肯定的前视断言 (？=)

假设我们想要匹配一个数的序列，该序列以一个圆点结束，但并不想把圆点作为模式匹配的一部分


teststr="123 456 789. 012"
m=/\d+("htmlcode">

teststr="a.c"
re=/#{Regexp.escape(teststr)}/
puts re.match("a.c")[0] #-> a.c
test=re.match("abc")
puts test[0] #-> Nil



正则表达式转换成字符串




puts /abc/.inspect #-> /abc/



使用正则表达式的常见方法：

  
用于if和while等
  
用于gsub、grep等
  
用于find_all、scan等

例如，puts "test 1 2 and test 3 4".scan(/\d/)会输出［"1","2","3","4"]。