如何用正则提取指定开头的可变长度CSV行的字段分组？

No problem at all—even with variable-length CSV lines, we can craft a regex that targets lines starting with tuesday and captures the rest of the fields (including empty ones). Let’s break this down based on exactly what you need:

Option 1: Capture All Subsequent Fields as a Single Group #

If you just need everything after the first tuesday field (including commas and empty spots) in one grouped chunk, this simple regex works perfectly—just make sure your tool enables multiline mode (usually flagged as m) so ^ and $ match the start/end of individual lines, not the whole text:

^tuesday,(.*)$

How it works: #

• ^ Anchors the match to the start of a line
• tuesday, Matches your target starting field plus the following comma
• (.*) Captures every character after that comma (including empty fields, extra commas, and text) into Group 1
• $ Anchors the match to the end of the line

Example Output:

For a line like tuesday,,apple,banana, Group 1 will be ,,apple,banana. For a line like tuesday, (only the starting field plus a comma), Group 1 will be an empty string.

Option 2: Capture Each Subsequent Field as Individual Groups #

If you need to grab each field separately (even empty ones), things get a bit trickier—but doable if your regex tool supports global matching (g flag) and the \G anchor (common in engines like PCRE):

(?:^tuesday,|\G(?!^))([^,]*)(?:,|$)

How it works: #

• (?:^tuesday,|\G(?!^)): Either matches the start of a tuesday line, or picks up right where the last match ended (ensures we only capture fields from the same target line)
• ([^,]*): Captures a single field (including empty fields—since [^,]* matches zero or more non-comma characters) into Group 1
• (?:,|$): Matches the comma separator or end of the line, moving us to the next field

Example Output:

For the line tuesday,,orange,, running this with global/multiline mode will return three matches for Group 1: "" (empty field), "orange", "" (final empty field).

Important Notes: #

• Double-check your tool’s regex support: Not all tools handle \G or multiline/global flags the same way.
• This assumes your CSV has no quoted fields with commas inside them—if you need to handle quoted fields, the regex gets way more complex, but your question didn’t mention that scenario, so we stuck to simple CSV.

内容的提问来源于stack exchange，提问作者snowbird