Home Backend Development PHP Tutorial PHP特殊字符如反斜杠处理函数addslashes()和stripslashes()的用法

PHP特殊字符如反斜杠处理函数addslashes()和stripslashes()的用法

Jun 20, 2016 pm 01:03 PM
php function

PHP自带的库函数 addslashes() 和 stripslashes() 都属于字符串处理类函数,作用正好相反:

addslashes():对输入字符串中的某些预定义字符前添加反斜杠,这样处理是为了数据库查询语句等的需要。这些预定义字符是:单引号 (') ,双引号 (") ,反斜杠 (\) ,NULL。

stripslashes():删除由 addslashes() 函数添加的反斜杠。该函数用于清理从数据库或 HTML 表单中取回的数据。(若是连续二个反斜杠,则去掉一个,保留一个;若只有一个反斜杠,就直接去掉。)

ps:默认情况下,PHP 指令 magic_quotes_gpc 为 on,对所有的 GET、POST 和 COOKIE 数据自动运行 addslashes()。不要对已经被 magic_quotes_gpc 转义过的字符串使用 addslashes(),因为这样会导致双层转义。遇到这种情况时可以使用函数 get_magic_quotes_gpc() 进行检测。例:

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if (get_magic_quotes_gpc()){

      code....

}

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addslashes() 例子:

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<?php

$str = "Who&#39;s John Adams?";

echo $str . " This is not safe in a database query.<br />";

echo addslashes($str) . " This is safe in a database query.";

?>

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输出:

Who's John Adams? This is not safe in a database query.
Who\'s John Adams? This is safe in a database query.

stripslashes() 例子:

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<?php

echo stripslashes("Who\&#39;s John Adams?");

?>

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输出:

Who's John Adams?


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