我真的是 Regex 的新手并且正在努力工作，但在我看来这已经超出了简单的范围。我了解如何在 .Net 中创建 Regex 对象，但我不确定一旦有了模式，如何将它用于我的特定目的。
Regex regex = new Regex("(at ){0,1}[0-9]{1,2}(:[0-9]{2}){0,1}(?:[ap]m?){0,1}");
我需要能够接受“晚餐将在晚上 9 点在你最喜欢的餐厅”这样的句子并获取值 {“晚餐将在你最喜欢的餐厅”，“晚上 9 点 "}(删除“at”，如果它存在)。
完整(？)测试用例:
"Dinner at 9pm" { "Dinner", "9pm" }
"Dinner at9pm" { "Dinner", "9pm" }
"Dinner 9pm" { "Dinner", "9pm" }
"Dinner 9p" { "Dinner", "9pm" }
"Dinner 9a" { "Dinner", "9am" }
"Dinner 9pZ" { "Dinner 9pZ", "" }
"Dinner 9aZ" { "Dinner 9aZ", "" }
"Dinner at 9" { "Dinner", "9" }
"Dinner at 9:15pm" { "Dinner", "9:15pm" }
"Dinner at 9:15" { "Dinner", "9:15" }
"Dinner at9:15" { "Dinner", "9:15" }
"Dinner at 9pm in Seattle" { "Dinner in Seattle", "9pm" }
"Dinner at9pmin Seattle" { "Dinner in Seattle", "9pm" }
"Dinner at9in Seattle" { "Dinner in Seattle", "9" }
"Dinner 9in Seattle" { "Dinner 9in Seattle", "" }
"9pm Dinner" { "Dinner", "9pm" }
"The 9pm Dinner was good" { "The Dinner as good", "9pm" }
"Dinner at 9pmpm" { "Dinner pm" "9pm" }
"Dinner at 9:15pmpm" { "Dinner pm" "9:15pm" }
(只是为了进一步说明，没有“:”或“am/pm”的数字必须以“at”开头，除非它是列出的第一个数字。“am”和“pm”需要以“结尾” M"或 "".)
除了测试用例之外，我不理解使用正则表达式对象(在上面的括号中列出)取回所需值所需的语法。
请您参考如下方法:
执行此操作的正则表达式会很复杂，而且在“晚上 9 点晚餐”等情况下也不会按预期顺序返回结果。如果你愿意花一点时间，写一个基本的 recursive-descent parser 可能会更简单。 .输入中的每个单词都会形成一个标记，您可以根据自己的要求轻松制定规则。例如:
event: "Dinner" time |
"Dinner" location |
"Dinner" time location |
"Dinner" location time
time: "at" number ":" number "am"/"pm"
/* etc. */
然后您为每个非终结符(事件、时间、位置等)编写一个小函数，该函数将完成其工作并返回结果。
如您所见，您的要求已经带来了如此多的可能性，以至于如果可能的话，正则表达式只会让它变得极其困惑。
