Best of Ruby Quiz - MadLib
题目大意明确,主要在于正则表达式运用
1]
首先是自己写的程序
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print str + "\n"
属于比较正常的算法型想法,流式替换过程
2]
然后是书上的程序,最简短的那个
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str = %q{Our favorite language is ((gem:a gemstone)). We think ((gem)) is
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better than ((a gemstone)). }
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hash = Hash.new do |hash,key|
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print "Give Me #{key.sub /\A([^:]+):/,"" } :"
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#p $1
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hash[$1] = gets.chomp
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end
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puts str.gsub(/\(\(([^\)]+)\)\)/){hash[$1]}
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#puts str.gsub(/\(\(([^\)]+)\)\)/ , hash[$1])
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稍微有些出入,大体一样
做一些分析:
[0]这个程序存在BUG,如果把第五行注释解开,可以看到输出的第一个$1 = "gem" ,第二个$2 = "nil",BUG在后面我的改进里有修正
[1]第八行用gsub的Block形式十分重要,以下是Programming Ruby的节选
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如果用第9行的形式,会出现$1 = nil 的错误,因为用参数形式$1不能正确配置
修正后的程序
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str = %q{Our favorite language is ((gem:a gemstone)). We think ((gem)) is
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better than ((a gemstone)). }
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hash = Hash.new do |hash,key|
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print "Give Me #{key.sub /^([^:]+):/,"" } :"
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#p $1 || key
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hash[$1 || key] = gets.chomp
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end
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puts str.gsub(/\(\(([^\)]+)\)\)/){hash[$1]}
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修正的结果可以将注释行解开验证