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Question

为什么不以下的后卫

(?<=to my\s)(checking|savings|CD) | (?<=to\s)(checking|savings|CD)

返回任何匹配：

Can you transfer from my CD 200 dollars to my checking, please?

尽管正确返回了匹配项（checking）：

Can you transfer from my CD 200 dollars to checking, please?

以下情况适用于两种情况：

(?<=from my\s)(checking|savings|CD) | (?<=from\s)(checking|savings|CD)

Can you transfer from my CD 200 dollars to checking, please? --> CD

Can you transfer from CD 200 dollars to checking, please?  --> CD

我正在尝试制定一个正则表达式，它能够在上面的加号中解析出目的地[后跟'到']以及以下文本字符串（或类似）：

- Transfer $20 from checking to savings please.
- Can you transfer from my CD 200 dollars to my checking, please?
- Please send from savings to checking 45.

Answer 1

也许你可以在没有外观的情况下做到这一点，然后让我的＆＃34;我的＆＃34;可选(?:my )?：

to (?:my )?(checking|savings|CD)

＆＃34;检查＆＃34;或者＆＃34;储蓄＆＃34;或者＆＃34; CD＆＃34;将被捕获​​的第1组。