正则表达式需求：匹配指定单词间不含特定字符串的内容

Your goal is to capture all substrings starting with The , ending with blue, and containing no cat in between. The regex you tried (The.*?(?!cat)blue) fails because the negative lookahead only checks right before "blue"—it doesn’t block "cat" from appearing earlier in the substring.

Correct Regex #

Here’s a regex that meets your requirements:

The (?:(?!cat).)*? blue 

Breakdown of the Regex #

Let’s break down why this works:

• The : Matches the exact starting sequence.
• (?:(?!cat).)*?: This non-capturing group ensures "cat" never appears in the middle:
  • (?!cat): Negative lookahead that checks the next three characters aren’t "cat".
  • .: Matches any single character (only if the lookahead passes).
  • *?: Non-greedy quantifier that stops immediately when it hits blue, preventing over-matching.
• blue: Matches the exact ending sequence.

Testing with Your Example String #

For your input string:

Dandelion The animal dog is blue The animal cat is blue Alcohol The animal cow is blue water

This regex will capture the two desired matches:

1. The animal dog is blue
2. The animal cow is blue

If you want to exclude the trailing space after "blue", adjust the regex to The (?:(?!cat).)*?blue (remove the space before blue), but ensure it aligns with your exact string structure.

内容的提问来源于stack exchange，提问作者Basque0407