零宽断言比较复杂。保存了一些示例待不时之需 ()表示捕获分组，()会把每个分组里的匹配的值保存起来，从左向右，以分组的左括号为标志，第一个出现的分组的组号为1，第二个为2，以此类推 (?:)表示非捕获分组，和捕获分组唯一的区别在于，非捕获分组匹配的值不会保存起来 正则表达式的先行断言和后行断言一共有 4 种形式：...

Phone number

123

This pattern needs to validate serial number

Accept regex in the form OutputType ServiceName ( InputType1 , InputType2 , . . . )

return an int

Accept long as first input argument

return a double, are named sum, and accept an arbitrary amount of doubles as input

strings represent messages in the form: from: "Sender", to: "Receiver", content: "Payload"

messages directed towards alice

messages have been sent to bob

Carry a payload which is either ping or pong

m

.

finding all anchor tags to help with removing their href attribute

Semantic Versioning to fix broken pkg-config

Semantic Versioning to fix broken pkg-config

Capture of chandlers wild good morning messages

For change var in config file on python

check dir is illegal or not