Powershell 正则表达式替换重复组

Question

我必须在这个字符串中添加逗号：1321654987.00 结果应该是：1,321,654,987.00

我正在尝试使用替换：

'123123897.00' -replace '^(?<start>(\d{1,3}))(?<mid>(\d{3}))*(?<end>(\.\d{2}))?$','${start},${mid}${end}'

但结果如下： 1,987.00

如何替换每个匹配的组，而不是最后一个？

提前致谢！

Answer 1

正则表达式可能是这样的

'123123897.00' -replace '(?m)(?<=[0-9])(?=(?:[0-9]{3})+(?![0-9]))', ','

说明

# (?<=[0-9])(?=(?:[0-9]{3})+(?![0-9]))
# 
# Options: Case sensitive; Exact spacing; Dot doesn't match line breaks; ^$ match at line breaks; Parentheses capture
# 
# Assert that the regex below can be matched, with the match ending at this position (positive lookbehind) «(?<=[0-9])»
#    Match a single character in the range between “0” and “9” «[0-9]»
# Assert that the regex below can be matched, starting at this position (positive lookahead) «(?=(?:[0-9]{3})+(?![0-9]))»
#    Match the regular expression below «(?:[0-9]{3})+»
#       Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
#       Match a single character in the range between “0” and “9” «[0-9]{3}»
#          Exactly 3 times «{3}»
#    Assert that it is impossible to match the regex below starting at this position (negative lookahead) «(?![0-9])»
#       Match a single character in the range between “0” and “9” «[0-9]»
# Your regular expression may find zero-length matches
#    PowerShell allows a zero-length match at the position where the previous match ends.
#    PowerShell advances one character through the string before attempting the next match if the previous match was zero-length.

话虽这么说，Mike 是对的，您应该使用格式化函数。以下就够了

"{0:N2}" -f 123123897.00

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