輸入是<p>The very <em>first</em> task is to find the beginning of a paragraph.</p><p>Then you have to find the end of the paragraph</p>預(yù)期的第一個輸出是（因為我使用貪婪量詞）<p>The very <em>first</em> task is to find the beginning of a paragraph.</p><p>Then you have to find the end of the paragraph</p>用于貪婪的代碼如下text = '''<p>The very <em>first</em> task is to find the beginning of a paragraph.</p><p>Then you have to find the end of the paragraph</p>'''pattern=re.compile(r'\<p\>.*\<\/p\>')data1=pattern.match(text,re.MULTILINE)print('data1:- ',data1,'\n')預(yù)期的第二個輸出是（因為我使用的是惰性量詞）<p>The very <em>first</em> task is to find the beginning of a paragraph.</p>用于懶惰的代碼如下text = '''<p>The very <em>first</em> task is to find the beginning of a paragraph.</p><p>Then you have to find the end of the paragraph</p>'''#pattern=re.compile(r'\<p\>.*?\<\/p\>')pattern=re.compile(r'<p>.*?</p>')data1=pattern.match(text,re.MULTILINE)print('data1:- ',data1,'\n')我得到的實際輸出都是 None
1 回答
蝴蝶刀刀
TA貢獻(xiàn)1801條經(jīng)驗 獲得超8個贊
你有幾個問題。首先，使用 時Pattern.match，第二個和第三個參數(shù)是位置參數(shù)，而不是標(biāo)志。需要將標(biāo)志指定為re.compile。其次，您應(yīng)該使用re.DOTALL來.匹配換行符，而不是re.MULTILINE.?最后 -match堅持匹配發(fā)生在字符串的開頭（在您的情況下是換行符），因此它不會匹配。您可能想改用Pattern.search。這適用于您的示例輸入：
pattern=re.compile(r'<p>.*</p>', re.DOTALL)
data1=pattern.search(text)
print('data1:- ',data1.group(0),'\n')
輸出：
data1:-? <p>
The very <em>first</em> task is to find the beginning of a paragraph.
</p>
<p>
Then you have to find the end of the paragraph
</p>?
單場比賽：
pattern=re.compile(r'<p>.*?</p>', re.DOTALL)
data1=pattern.search(text)
print('data1:- ',data1.group(0),'\n')
輸出：
data1:-? <p>
The very <em>first</em> task is to find the beginning of a paragraph.
</p>?
另請注意/， ,<和>在正則表達(dá)式中沒有特殊含義，不需要轉(zhuǎn)義。我已經(jīng)在上面的代碼中刪除了它。
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