感谢此答案，我能够在最初认为不可能的情况下找到解决问题的方法.

Thanks to this answer, I was able to find a solution to your problem after initially thinking it wasn't possible.

在Notepad ++中执行此操作的方法是使用以下选项:

The way to do this in Notepad++ is to use the following options:

• 打开替换"对话框( Ctrl + H )
• 查找内容:^([^:]+:)(([A-Z])|([a-z]))([^:]+)$
• 替换为:$1\L$3\E\U$4\E$5
• 检查匹配情况
• 检查环绕
• 选择正则表达式
• 取消选中.匹配换行符
• 按全部替换

• Open the Replace dialog (Ctrl + H)
• Find what: ^([^:]+:)(([A-Z])|([a-z]))([^:]+)$
• Replace with: $1\L$3\E\U$4\E$5
• Check Match case
• Check Wrap around
• Select Regular expression
• Uncheck . matches newline
• Press Replace All

以下是此操作的GIF:

Here's a GIF of this in action:

查找内容字段的细分:

正则表达式前面的
• ^代表行的开头，结尾的$代表行的结尾.这样可以防止它变得懒惰或换行.
• ([^:]+:)代表该行开头的字符，允许除:之外的所有字符.这是组$1
• (([A-Z])|([a-z]))表示:之后的第一个字符.如果除了大写或小写字母外，其他任何内容都将跳过该行.
  • 组$2将是第一个字符，无论大小写如何.我们将在替代产品时忽略它.
  • 组$3如果是大写字母，将是第一个字符，否则$3将为空.
  • 组$4如果是小写字母，将是第一个字符，否则$4将为空.
  • ^ at the front of the Regular Expression represents the beginning of a line and $ at the end represents the end of a line. This prevents it from being lazy or wrapping to the next line.
  • ([^:]+:) represents the characters at the beginning of the line, allowing all characters except :. This is group $1
  • (([A-Z])|([a-z])) represents the first character after the :. If there is anything other than an upper or lowercase letter, it will skip the line.
    • Group $2 will be the first character, regardless of uppercase or lowercase. We'll ignore this in our replacement.
    • Group $3 will be the first character if it is uppercase, otherwise $3 will be empty.
    • Group $4 will be the first character if it is lowercase, otherwise $4 will be empty.

    替换为字段的明细:

    • $1将是如上所述的第一组
    • \L$3\E将如上所述将组$3转换为小写.
    • \U$4\E' will convert group $ 4`如上所述，为大写字母.
    • $5将是如上所述的最后一组
    • $1 will be the first group as described above
    • \L$3\E will convert group $3 as described above to lowercase.
    • \U$4\E' will convert group$4` as described above to uppercase.
    • $5 will be the last group as described above

    \L和\U分别表示开始转换为小写"或大写". \E代表停止转换".由于$3或$4中只有一个包含第一个字符(另一个将为空白)，因此仅在需要时才进行转换.

    \L and \U stand for "beginning converting to lowercase" or "uppercase," respectively. \E stands for "stop converting." Since only one out of $3 or $4 will contain the first character (the other will be blank), this converts only in the case we want.