java - 正则表达式二进制字符串至少包含并以以下结尾

Question

问题涉及为二进制字符串编写正则表达式。

如何编写一个以 00 结尾的代码，以及另一个包含至少三个 1 的代码？

Answer 1

以00结尾:

^[01]*00$

包含至少三个1:

^(?=.*(?:0*1){3})[01]*$

两者:

^(?=.*(?:0*1){3})[01]*00$

说明:

^        # Start of string
(?=      # Assert that the following could be matched here:
 .*      # Any number of characters
 (?:0*1) # followed by any number of 0s and exactly one 1
 {3}     # three times
)        # End of lookahead
[01]*    # Match any number of ones or zeroes
00       # Match two zeroes
$        # at the end of the string

由于字符串可能只包含 1 和 0，因此我们实际上不需要向前查找。以下内容也适用(但仅在这些具体情况下):

^(?:0*1){3}[01]*00$