Question

我正在尝试将1+2和1*2/3....等mathematica表达式与无穷大相匹配。有人可以解释为什么我的正则表达式匹配下面的最后一个案例，以及如何修复它以便它只匹配有效的表达式（可能永远延伸）？

perms=["12+2*4","2+2","-2+","12+34-"]
perms.each do |line|
    puts "#{line}=#{eval(line)}" if line =~ /^\d+([+-\/*]\d+){1,}/
end

我希望输出为：

12+2*4=20
2+2=4

Answer 1

在> dput(droplevels(head(df))) structure(list(SOX2 = c("4-acetylantroquinonol B", "arsenite", "Estradiol", "bisphenol A", "butyraldehyde", "C646 compound"), EGR1 = c("1,10-phenanthroline", "1-nitropyrene", "2,2,4,4-tetrabromodiphenyl ether", "2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one", "22-hydroxycholesterol", "2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine"), FOS = c("1-nitropyrene", "2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate", "2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one", "22-hydroxycholesterol", "2,4-dinitrotoluene", "2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine" ), RUNX2 = c("2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one", "Acetylcysteine", "arsenic trioxide", "Ascorbic Acid", "7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide", "Estradiol")), .Names = c("SOX2", "EGR1", "FOS", "RUNX2"), row.names = c(NA, 6L), class = "data.frame")内，[character set]字符定义范围字符 - 考虑-或[a-z]。如果您想匹配文字[0-9]，则必须是第一个或最后一个字符。

其他事项：/^\d+(?:[+\/*-]\d+)+$/正是{1,};你也需要在最后锚定，所以你不能匹配+

Answer 2

您应该使用$完成表达式以匹配整个输入字符串：

/^\d+([-+\/*]\d+){1,}$/

连字符-的错误位置是表达式中的一个错误来源。缺少$另一个。

重复正则表达式匹配数学符号然后编号失败

2 个答案: