php中preg正则函数使用

<?php//注：正则 /a.+?e/ 是非贪婪模式(因为量词‘+’后面加上了‘?’)，如果使用 /a.+?e/U 则变回了贪婪模式preg_match("/a.+?e/","abcdefgabcdefgabcdefg",$out1);preg_match_all("/a.+?e/","abcdefgabcdefgabcdefg",$out2);var_dump($out1);var_dump($out2);/*输出：array (size=1)  0 => 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) */?>

<?php$str = "http://www.baidu/.com?url=www.sina.com/";preg_match("/http:(.*)com/", $str, $matches1); //贪婪匹配var_dump($matches1);preg_match("/http:(.*?)com/", $str, $matches2); //非贪婪匹配(量词'*'后面跟上了'?')var_dump($matches2);/*array (size=2)  0 => 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) */?>

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

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