Python 正则表达式lookbehind 和lookahead

Python正则表达式lookbehind和lookahead的用法

python
import re
pattern = r'(?<=green )apple'
text = 'I have a green apple'
match = re.search(pattern, text)
if match:
    print(match.group())  # 输出: apple

python
import re
pattern = r'apple(?= pie)'
text = 'I have an apple pie'
match = re.search(pattern, text)
if match:
    print(match.group())  # 输出: apple

python
import re
pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.(?!example)[A-Za-z]{2,}\b'
text = 'Contact us at support@example.com or info@domain.com'
matches = re.findall(pattern, text)
for match in matches:
    print(match)  # 输出: info@domain.com