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正则表达式内容

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The special characters are:

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Characters Means “.” Matches any character except a newline. “^” Matches the start of the string. “$” Matches the end of the string or just before the newline at the end of the string. “*” Matches 0 or more (greedy) repetitions of the preceding RE. Greedy means that it will match as many repetitions as possible. “+” Matches 1 or more (greedy) repetitions of the preceding RE. “?” Matches 0 or 1 (greedy) of the preceding RE. *?,+?,?? Non-greedy versions of the previous three special characters. {m,n} Matches from m to n repetitions of the preceding RE. {m,n}? Non-greedy version of the above. “\” Either escapes special characters or signals a special sequence. [] Indicates a set of characters. A “^” as the first character indicates a complementing set. “|” A|B, creates an RE that will match either A or B. (…) Matches the RE inside the parentheses. The contents can be retrieved or matched later in the string. (?aiLmsux) Set the A, I, L, M, S, U, or X flag for the RE (see below). (?:…) Non-grouping version of regular parentheses. (?P…) The substring matched by the group is accessible by name. (?P=name) Matches the text matched earlier by the group named name. (?#…) A comment; ignored. (?=…) Matches if … matches next, but doesn’t consume the string. (?!…) Matches if … doesn’t match next. (?<=…) Matches if preceded by … (must be fixed length). (? Matches if not preceded by … (must be fixed length). (?(id/name)yes|no) Matches yes pattern if the group with id/name matched, the (optional) no pattern otherwise.

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