php中preg正則函數使用_PHP教程

php中preg正則函數使用

1.preg_match和preg_match_all的區別
preg_match和 preg_match_all區別是preg_match只匹配一次。而preg_match_all全部匹配，直到字串結束。例：

 string 'abcde' (length=5)array (size=1)  0 =>    array (size=3)      0 => string 'abcde' (length=5)      1 => string 'abcde' (length=5)      2 => string 'abcde' (length=5) */?>

2.貪婪模式和非貪婪模式的區別
如：String str="abcaxc";
　　Patter p="ab*c";
貪婪匹配:Regex一般趨向於最大長度匹配，也就是所謂的貪婪匹配。如上面使用模式p匹配字串str，結果就是匹配到：abcaxc(ab*c)。
非貪婪匹配：就是匹配到結果就好，較少的匹配字元。如上面使用模式p匹配字串str，結果就是匹配到：abc(ab*c)。
例：

 string 'http://www.baidu/.com?url=www.sina.com' (length=38)  1 => string '//www.baidu/.com?url=www.sina.' (length=30)array (size=2)  0 => string 'http://www.baidu/.com' (length=21)  1 => string '//www.baidu/.' (length=13) */?>

3.preg_match_all參數PREG_PATTERN_ORDER(預設)和PREG_SET_ORDER的區別

]+>(.*)]+>|U",    "start: this is a testend",    $out1);var_dump($out1);echo('PREG_SET_ORDER');preg_match_all("|<[^>]+>(.*)]+>|U",    "start: this is a testend",    $out2, PREG_SET_ORDER);var_dump($out2);/*PREG_PATTERN_ORDERarray (size=2)  0 =>    array (size=3)      0 => string 'start: ' (length=14)      1 => string 'this is a test' (length=21)      2 => string 'end' (length=10)  1 =>    array (size=3)      0 => string 'start: ' (length=7)      1 => string 'this is a test' (length=14)      2 => string 'end' (length=3)PREG_SET_ORDERarray (size=3)  0 =>    array (size=2)      0 => string 'start: ' (length=14)      1 => string 'start: ' (length=7)  1 =>    array (size=2)      0 => string 'this is a test' (length=21)      1 => string 'this is a test' (length=14)  2 =>    array (size=2)      0 => string 'end' (length=10)      1 => string 'end' (length=3) */?>

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