正則表達式在PHP

Question

附加重複的字符串。例如，我有一個這樣的字符串：

Line 1 
<br/> 
<br/> 
Line 2 
<br/> 
<br/> 
<br/> 
Line 3 

我需要檢測和更換複製和連接字符串，如<br/>的，因此將只有1 <br/>代替。所以，最後的結果我想到的是：

Line 1 
<br/> 
Line 2 
<br/> 
Line 3 

任何人都可以幫助我的正則表達式？解釋將不勝感激。

Answer 1

preg_replace('/(.{3,})\\1+/s', '\\1', $string); 

這將取代的3個字符以上重複的字符串的任何序列。

這裏試試：http://ideone.com/5ew7X

如果你想只更換<br/> S：

preg_replace('/(<br\/>\s*){2,}/s', '\\1', $string); 

Answer 2

不是你的正則表達式問題的直接答案，仍然考慮使用sed來做它;禮貌Eric Pement's sed one-liners。

# delete duplicate, consecutive lines from a file (emulates "uniq"). 
# First line in a set of duplicate lines is kept, rest are deleted. 
sed '$!N; /^\(.*\)\n\1$/!P; D' 

# delete duplicate, nonconsecutive lines from a file. Beware not to 
# overflow the buffer size of the hold space, or else use GNU sed. 
sed -n 'G; s/\n/&&/; /^\([ -~]*\n\).*\n\1/d; s/\n//; h; P' 

# delete all lines except duplicate lines (emulates "uniq -d"). 
sed '$!N; s/^\(.*\)\n\1$/\1/; t; D'