PHP returns the function addslashes() that adds a backslash before a predefined character-PHP Tutorial-php.cn

Example

Add a backslash before each double quote ("):

<?php 
$str = addslashes(&#39;What does "yolo" mean?&#39;);
echo($str); 
?>

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Definition and usage

addslashes() function returns the predefined characters Strings preceded by a backslash:

Single quotation mark (')

Double quotation mark (")

Backslash. Bar (\)

NULL

Tip: This function can be used to prepare appropriate strings for strings stored in the database and database query statements.

Note: By default, the PHP instruction magic_quotes_gpc is on, automatically running addslashes() for all GET, POST and COOKIE data. Do not use addslashes() on strings that have been escaped by magic_quotes_gpc, as this will result in double escaping. When encountering this situation, you can

use the function

get_magic_quotes_gpc() for detection. Syntax

addslashes(string)

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ParametersstringTechnical details

Description
Required. Specifies the string to be escaped.

Return value: PHP version:

更多实例

向字符串中的预定义字符添加反斜杠：

<?php
$str = "Who&#39;s Peter Griffin?";
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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php addslashes函数的作用是在预定义的字符前面加上反斜杠，这些预定义字符包括：

单引号（'）

双引号（"）

反斜杠（\）

NULL

addslashes函数经常使用在向数据库插入数据时，比如有一个字符串

$str="my name&#39;s wxp";

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现在要将这个字符串插入到数据库表中，由于该字符串有单引号'，这样很可能与mysql拼接字符串的单引号'冲突，导致SQL语句不正确，也就无法正常执行插入操作，此时我们需要使用addslashes函数处理这个字符串。如：

$str="my name&#39;s wxp";echo addslashes($str);//输出my name\'s wxp

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然后在拼接mysql字符串：

$sql="insert into student(student_name)values(&#39;".addslashes($str)."&#39;)";
mysql_query($sql);

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此时字符串被插入到数据库，那么大家是否知道插入的字符串是带反斜杠还是不带反斜杠呢？恐怕很多人都会认为肯定是带反斜杠的字符串。其实这个答案是错误的，插入的字符串是没有带反斜杠。至于为什么插入的字符串在数据库中是没有加反斜杠，请大家继续看下面讲解。

如果字符串$str="my name's wxp"是使用POST和GET提交的数据，这个时候插入数据库中的数据是带反斜杠的，由此可知addslashes只是在POST和GET数据插入数据库时才会把反斜杠同时插入到数据库，其他情况下不会将反斜杠插入到数据库。

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Returns the escaped string.
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