php preg_match_all的解釋

Question

我是新來的PHP和困惑的preg_match_all（）函數。

有人可以解釋什麼功能的每個部分在這個例子中做？

preg_match_all("/<item><title>([^<]*) - ([^<]*?)<\/title>/i", $buffer, $titlematches); 

Answer 1

這是一個正則表達式，它們是棘手的混蛋，直到你習慣生活在其中。它們不僅適用於PHP，每種語言都具有使用它們的功能。

這是搜索$buffer，在<item>元素內尋找<title>元素。它正在尋找<title>元素中的兩個由-分隔的文本塊（第二個塊是可選的）。找到的文本塊保存到$titlematches以供在腳本中使用。

正如在其他答案中提到的，http://regex101.com/是一個很好的資源來檢查你的語法，但可能不適合初學者！

Answer 2

/([^<]) - ([^<]?)<\/title>/i 
1st Capturing group ([^<]) 
[^<] match a single character not present in the list below 
< a single character in the list < literally (case insensitive) 
- matches the characters - literally 
2nd Capturing group ([^<]?) 
[^<]? match a single character not present in the list below 
Quantifier: ? Between zero and one time, as many times as possible, giving back as needed [greedy] 
< a single character in the list < literally (case insensitive) 
< matches the characters < literally 
\/ matches the character/literally 
title> matches the characters title> literally (case insensitive) 
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z]) 

https://regex101.com/