这里有一个方法可以实现您想要的功能：

Option Explicit
Function Snake_case(s As String) As String
    Dim RE As Object
    Const sPat As String = "([A-Za-z0-9]+)(?=[ _A-Z])[ _]?(\S+)"
    Const sRepl As String = "$1_$2"
    Dim v As Variant

Set RE = CreateObject("vbscript.regexp")
With RE
    .Global = True
    .ignorecase = False
    .Pattern = sPat
    v = Split(.Replace(s, sRepl), "_")
End With

v(0) = WorksheetFunction.Proper(v(0))
v(1) = LCase(v(1))
Snake_case = Join(v, "_")

End Function

字符串
x1c 0d1x的数据
下面是正则表达式和替换字符串的解释：

Snake_case转换

([A-Za-z0-9]+)(?=[ _A-Z])[ _]?(\S+)

型
选项：区分大小写;^$换行匹配

• Match the regex below and capture its match into backreference number 1([A-Za-z0-9]+)
• Match a single character present in the list below[A-Za-z0-9]+
• Between one and unlimited times, as many times as possible, giving back as needed (greedy)+
• A character in the range between “A” and “Z”A-Z
• A character in the range between “a” and “z”a-z
• A character in the range between “0” and “9”0-9
• Assert that the regex below can be matched starting at this position (positive lookahead)(?=[ _A-Z])
• Match a single character present in the list below[ _A-Z]
• A single character from the list “ _”_
• A character in the range between “A” and “Z”A-Z
• Match a single character from the list “ _”[ _]?
• Between zero and one times, as many times as possible, giving back as needed (greedy)?
• Match the regex below and capture its match into backreference number 2(\S+)
• Match a single character that is NOT a “whitespace character”\S+
• Between one and unlimited times, as many times as possible, giving back as needed (greedy)+

$1_$2

• Insert the text that was last matched by capturing group number 1$1
• Insert the character “_” literally_
• Insert the text that was last matched by capturing group number 2$2

使用RegexBuddy创建

罗恩·罗森菲尔德的解决方案对我不起作用。我用这个代替。在论坛https://www.mrexcel.com/board/threads/camelcase-to-proper-case.381040/上取了类似的

Option Explicit
Function ToSnakeCase(txt As String) As String
'
' If cell A1 contains: SanFrancisco
' cell B1: =ToSnakeCase(A1)
' cell B1: San_Francisco
'
Dim Hold As String, i As Long
Hold = Left(txt, 1)
For i = 2 To Len(txt) Step 1
  If Asc(Mid(txt, i, 1)) > 96 Then
    Hold = Hold & Mid(txt, i, 1)
  Else
    Hold = Hold & "_" & Mid(txt, i, 1)
  End If
Next i
ToSnakeCase = Hold
End Function

字符串