如何删除Notepad++以外的所有内容？提取userId附近的ID

Hey there! Let's tackle your two Notepad++ tasks step by step—super straightforward once you know the regex tricks.

The easiest way to strip out unwanted content is using regular expression replace. Here's how:

• Hit Ctrl+H to open the Replace window.
• Switch to the "Regular expression" mode (make sure "Wrap around" is checked; tick "Match newline" if you need to target content across lines).
• Example scenario: If you only want to keep lines that mention "userId", use this setup:
  • Find what: ^(?!.*userId).*$\r?\n?
  • Replace with: (leave this blank)
  • Click "Replace All"—boom, all lines without "userId" are instantly removed.
• If you need to preserve a specific format (like all id: XXX entries), adjust the regex to target your desired content, or use the "Find All in Current Document" feature: search for your target pattern, right-click the matches, select "Copy All", then paste into a new clean document.

Since you didn't share the exact required output style, I'll give you a flexible regex method you can tweak to fit your needs:
First, identify how your userId is formatted (e.g., "userId": "12345", userId=abc789, etc.). Let's walk through two common cases:

Case 1: JSON-style "userId": "12345" #

• Open Replace (Ctrl+H) → Regular expression mode.
• Find what: .*"userId": "(\d+)".*
• Replace with: $1 (or your desired format, like User ID: $1 if you need labels for each entry)
• Click "Replace All", then go to Edit > Line Operations > Remove Empty Lines to clean up leftover blank rows.

Case 2: Plain text userId=abc789 (alphanumeric IDs) #

• Find what: .*userId=(\w+).*
• Replace with: $1 (or your custom style)
• Run the same empty line cleanup step as above to tidy the result.

If you need to keep a bit of context around the userId (like the line before/after), use a multi-line regex. For example, to keep the userId line plus the line immediately after:

• Find what: .*userId.*\r?\n.*\r?\n?
• Replace with: $0 (this retains the matched content)
• Then remove any remaining empty lines to polish the final output.

内容的提问来源于stack exchange，提问作者Mostafa A alsharqawy