用#hash解釋preg_match語法

Question

請問您能解釋一下這個preg_match代碼在做什麼！ 我也不明白爲什麼它以＃標籤開頭？

if (!preg_match('#\.(.+)$#', $file['name'][$key], $matches)) {..;} 

Answer 1

首先，它測試，如果正則表達式不匹配（!preg_match）以下：

#\.(.+)$# 
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Match the character 「#」 literally «#» 
Match the character 「.」 literally «\.» 
Match the regex below and capture its match into backreference number 1 «(.+)» 
    Match any single character that is NOT a line break character (line feed) «.+» 
     Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+» 
Assert position at the end of a line (at the end of the string or before a line break character) (line feed) «$» 
Match the character 「#」 literally «#» 

我不能幫你$file['name'][$key]，因爲我不知道它是什麼，它似乎是一個filename。