略微加速

PHP官方手册 - 互联网笔记

PHP - Manual: addslashes

2024-04-28

addslashes

(PHP 4, PHP 5, PHP 7, PHP 8)

addslashes — 使用反斜线引用字符串

说明

addslashes(string $str): string

返回字符串，该字符串为了数据库查询语句等的需要在某些字符前加上了反斜线。这些字符是单引号（'）、双引号（"）、反斜线（\）与 NUL（null 字符）。

一个使用 addslashes() 的例子是当你要往数据库中输入数据时。 例如，将名字 O'reilly 插入到数据库中，这就需要对其进行转义。 强烈建议使用 DBMS 指定的转义函数 （比如 MySQL 是 mysqli_real_escape_string()，PostgreSQL 是 pg_escape_string()），但是如果你使用的 DBMS 没有一个转义函数，并且使用 \ 来转义特殊字符，你可以使用这个函数。 仅仅是为了获取插入数据库的数据，额外的 \ 并不会插入。 当 PHP 指令 magic_quotes_sybase 被设置成 on 时，意味着插入 ' 时将使用 ' 进行转义。

PHP 5.4 之前 PHP 指令 magic_quotes_gpc 默认是 on， 实际上所有的 GET、POST 和 COOKIE 数据都用被 addslashes() 了。 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。

参数

str

要转义的字符。

返回值

返回转义后的字符。

范例

示例 #1 一个 addslashes() 例子

<?php
$str = "Is your name O'reilly?";

// 输出： Is your name O\'reilly?
echo addslashes($str);
?>

参见

add a noteadd a note

User Contributed Notes 19 notes

up
16
roysimke at microsoftsfirstmailprovider dot com
12 years ago
Never use addslashes function to escape values you are going to send to mysql. use mysql_real_escape_string or pg_escape at least if you are not using prepared queries yet.

keep in mind that single quote is not the only special character that can break your sql query. and quotes are the only thing which addslashes care.
up
10
hoskerr at nukote dot com
19 years ago
Beware of using addslashes() on input to the serialize() function.   serialize() stores strings with their length; the length must match the stored string or unserialize() will fail. 

Such a mismatch can occur if you serialize the result of addslashes() and store it in a database; some databases (definitely including PostgreSQL) automagically strip backslashes from "special" chars in SELECT results, causing the returned string to be shorter than it was when it was serialized.

In other words, do this...

<?php
$string="O'Reilly";
$ser=serialize($string);    # safe -- won't count the slash
$result=addslashes($ser);
?>

...and not this...

<?php
$string="O'Reilly";
$add=addslashes($string);   # RISKY!  -- will count the slash
$result=serialize($add);
?>

In both cases, a backslash will be added after the apostrophe in "O'Reilly"; only in the second case will the backslash be included in the string length as recorded by serialize().

[Note to the maintainers: You may, at your option, want to link this note to serialize() as well as to addslashes().  I'll refrain from doing such cross-posting myself...]
up
7
svenr at selfhtml dot org
11 years ago
To output a PHP variable to Javascript, use json_encode().

<?php

$var = "He said \"Hello O'Reilly\" & disappeared.\nNext line...";
echo "alert(".json_encode($var).");\n";

?>

Output:
alert("He said \"Hello O'Reilly\" & disappeared.\nNext line...") ;
up
2
geekcom
2 years ago
For PHP 7.3.* use FILTER_SANITIZE_ADD_SLASHES.

<?php
$str = "Is your name O'Reilly?";
$strWithSlashes = filter_var($str, FILTER_SANITIZE_ADD_SLASHES);

// Outputs: Is your name O\'Reilly?
echo $strWithSlashes;

?>
up
3
hybrid at n0spam dot pearlmagik dot com
21 years ago
Remember to slash underscores (_) and percent signs (%), too, if you're going use the LIKE operator on the variable or you'll get some unexpected results.
up
3
unsafed
17 years ago
addslashes does NOT make your input safe for use in a database query! It only escapes according to what PHP defines, not what your database driver defines. Any use of this function to escape strings for use in a database is likely an error - mysql_real_escape_string, pg_escape_string, etc, should be used depending on your underlying database as each database has different escaping requirements. In particular, MySQL wants \n, \r and \x1a escaped which addslashes does NOT do. Therefore relying on addslashes is not a good idea at all and may make your code vulnerable to security risks. I really don't see what this function is supposed to do.
up
0
divinity76 at gmail dot com
3 months ago
Addslashes is *never* the right answer, it's (ab)use can lead to security exploits!

if you need to escape HTML, it's (unfortunately)
<?php
echo htmlentities($html, ENT_QUOTES|ENT_SUBSTITUTE|ENT_DISALLOWED);
?>
if you need to quote shell arguments, it's
<?php
$cmd.= " --file=" . escapeshellarg($arg);
?>
if you need to quote SQL strings it's
<?php
$sql.= "WHERE col = '".$mysqli->real_escape_string($str)."'";
?>
or
<?php
$sql.= "WHERE col = " . $pdo->quote($str);
?>
if you need to quote javascript/json strings its
<?php
let str = <?=json_encode($str, JSON_THROW_ON_ERROR);?>;
?>

if you need to quote a string in xpath it's
<?php
//based on https://stackoverflow.com/a/1352556/1067003
function xpath_quote(string $value):string{
    if(false===strpos($value,'"')){
        return '"'.$value.'"';
    }
    if(false===strpos($value,'\'')){
        return '\''.$value.'\'';
    }
    // if the value contains both single and double quotes, construct an
    // expression that concatenates all non-double-quote substrings with
    // the quotes, e.g.:
    //
    //    concat("'foo'", '"', "bar")
    $sb='concat(';
    $substrings=explode('"',$value);
    for($i=0;$i<count($substrings);++$i){
        $needComma=($i>0);
        if($substrings[$i]!==''){
            if($i>0){
                $sb.=', ';
            }
            $sb.='"'.$substrings[$i].'"';
            $needComma=true;
        }
        if($i < (count($substrings) -1)){
            if($needComma){
                $sb.=', ';
            }
            $sb.="'\"'";
        }
    }
    $sb.=')';
    return $sb;
}
$xp->query('/catalog/items/item[title='.xpath_quote($var).']');
?>
if you need to quote strings in CSS its
<?php
// CSS escape code ripped from Zend Framework ( https://github.com/zendframework/zf2/blob/master/library/Zend/Escaper/Escaper.php )
function css_escape_string($string)
{
    $cssMatcher = function ($matches) {
        $chr = $matches[0];
        if (strlen($chr) == 1) {
            $ord = ord($chr);
        } else {
            $chr = mb_convert_encoding($chr, 'UTF-16BE', 'UTF-8'); // $this->convertEncoding($chr, 'UTF-16BE', 'UTF-8');
            $ord = hexdec(bin2hex($chr));
        }
        return sprintf('\\%X ', $ord);
    };
    $originalEncoding = mb_detect_encoding($string);
    if ($originalEncoding === false) {
        $originalEncoding = 'UTF-8';
    }
    ;
    $string = mb_convert_encoding($string, 'UTF-8', $originalEncoding); // $this->toUtf8($string);
                                                                        // throw new Exception('mb_convert_encoding(\''.$string.'\',\'UTF-8\',\''.$originalEncoding.'\');');
    if ($string === '' || ctype_digit($string)) {
        return $string;
    }
    $result = preg_replace_callback('/[^a-z0-9]/iSu', /*$this->*/$cssMatcher, $string);
    // var_dump($result);
    return mb_convert_encoding($result, $originalEncoding, 'UTF-8'); // $this->fromUtf8($result);
}

?>

- but never addslashes.
up
0
David Spector
8 years ago
If all you want to do is quote a string as you would normally do in PHP (for example, when returning an Ajax result, inside a json string value, or when building a URL with args), don't use addslashes (you don't want both " and ' escaped at the same time). Instead, just use this function:

<?php
function Quote($Str) // Double-quoting only
    {
    $Str=str_replace('"','\"',$Str);
    return '"'.$Str.'"';
    } // Quote
?>

Modify this easily to get a single-quoting function.
up
0
stuart at horuskol dot co dot uk
13 years ago
Be careful on whether you use double or single quotes when creating the string to be escaped:

$test = 'This is one line\r\nand this is another\r\nand this line has\ta tab';

echo $test;
echo "\r\n\r\n";
echo addslashes($test);

$test = "This is one line\r\nand this is another\r\nand this line has\ta tab";

echo $test;
echo "\r\n\r\n";
echo addslashes($test);
up
0
Nate from RuggFamily.com
15 years ago
If you want to add slashes to special symbols that would interfere with a regular expression (i.e., . \ + * ? [ ^ ] $ ( ) { } = ! < > | :), you should use the preg_quote() function.
up
0
Adrian C
15 years ago
What happends when you add addslashes(addslashes($str))? This is not a good thing and it may be fixed:

function checkaddslashes($str){       
    if(strpos(str_replace("\'",""," $str"),"'")!=false)
        return addslashes($str);
    else
        return $str;
}

checkaddslashes("aa'bb");  => aa\'bb
checkaddslashes("aa\'bb"); => aa\'bb
checkaddslashes("\'"); => \'
checkaddslashes("'");  => \'

Hope this will help you
up
0
Picky
16 years ago
This function is deprecated in PHP 4.0, according to this article:

http://www.newsforge.com/article.pl?sid=06/05/23/2141246

Also, it is worth mentioning that PostgreSQL will soon start to block queries involving escaped single quotes using \ as the escape character, for some cases, which depends on the string's encoding.  The standard way to escape quotes in SQL (not all SQL databases, mind you) is by changing single quotes into two single quotes (e.g, ' ' ' becomes ' '' ' for queries).

You should look into other ways for escaping strings, such as "mysql_real_escape_string" (see the comment below), and other such database specific escape functions.
up
0
hazy underscore fakie at ringwraith dot org
18 years ago
Note that when using addslashes() on a string that includes cyrillic characters, addslashes() totally mixes up the string, rendering it unusable.
up
0
php at slamb dot org
19 years ago
spamdunk at home dot com, your way is dangerous on PostgreSQL (and presumably MySQL). You're quite correct that ANSI SQL specifies using ' to escape, but those databases also support \ for escaping (in violation of the standard, I think). Which means that if they pass in a string that includes a "\'", you expand it to "\'''" (an escaped quote followed by a non-escaped quote. WRONG! Attackers can execute arbitrary SQL to drop your tables, make themselves administrators, whatever they want.)

The best way to be safe and correct is to:

- don't use magic quotes; this approach is bad. For starters, that's making the assumption that you will be using your input in a database query, which is arbitrary. (Why not escape all "<"s with "&lt;"s instead? Cross-site scripting attacks are quite common as well.) It's better to set up a way that does whatever escaping is correct for you when you use it, as below:

- when inserting into the database, use prepared statements with placeholders. For example, when using PEAR DB:

<?php
    $stmt = $dbh->prepare('update mb_users set password = ? where username = ?');
    $dbh->execute($stmt, array('12345', 'bob'));
?>

Notice that there are no quotes around the ?s. It handles that for you automatically. It's guaranteed to be safe for your database. (Just ' on oracle, \ and ' on PostgreSQL, but you don't even have to think about it.)

Plus, if the database supports prepared statements (the soon-to-be-released PostgreSQL 7.3, Oracle, etc), several executes on the same prepare can be faster, since it can reuse the same query plan. If it doesn't (MySQL, etc), this way falls back to quoting code that's specifically written for your database, avoiding the problem I mentioned above.

(Pardon my syntax if it's off. I'm not really a PHP programmer; this is something I know from similar things in Java, Perl, PL/SQL, Python, Visual Basic, etc.)
up
-1
luciano at vittoretti dot com dot br
16 years ago
Note, this function wont work with mssql or access queries.
Use the function above (work with arrays too).

function addslashes_mssql($str){
    if (is_array($str)) {
        foreach($str AS $id => $value) {
            $str[$id] = addslashes_mssql($value);
        }
    } else {
        $str = str_replace("'", "''", $str);   
    }
   
    return $str;
}

function stripslashes_mssql($str){
    if (is_array($str)) {
        foreach($str AS $id => $value) {
            $str[$id] = stripslashes_mssql($value);
        }
    } else {
        $str = str_replace("''", "'", $str);   
    }

    return $str;
}
up
-2
Lars
10 years ago
Even for simple json string backslash encodings, do not use this function. Some tests may work fine, but in json the single quote (') must not be escaped.
up
-2
joechrz at gmail dot com
15 years ago
Here's an example of a function that prevents double-quoting, I'm surprised noone has put something like this up yet... (also works on arrays)

<?php
function escape_quotes($receive) {
    if (!is_array($receive))
        $thearray = array($receive);
    else
        $thearray = $receive;
   
    foreach (array_keys($thearray) as $string) {
        $thearray[$string] = addslashes($thearray[$string]);
        $thearray[$string] = preg_replace("/[\\/]+/","/",$thearray[$string]);
    }
   
    if (!is_array($receive))
        return $thearray[0];
    else
        return $thearray;
}
?>
up
-2
DarkHunterj
12 years ago
Based on:
Danijel Pticar
05-Aug-2009 05:22
I recommend this extended version, to replace addslashes altogether(works for both strings and arrays):
<?php
function addslashesextended(&$arr_r)
{
    if(is_array($arr_r))
    {
        foreach ($arr_r as &$val)
            is_array($val) ? addslashesextended($val):$val=addslashes($val);
        unset($val);
    }
    else
        $arr_r=addslashes($arr_r);
}
?>
up
-3
baburaj dot ambalam at gmail dot com
1 year ago
escape '$'  using backslash '\$'

<?php

  $evalStr = "5 + 3";
  $sum = 0; 
  $evalStr = " \$sum = ". $evalStr.";"; 
  eval( $evalStr);
  print ("sum ".$sum);

?>
add a noteadd a note

官方地址：https://www.php.net/manual/en/function.addslashes.php

有任何技术问题请点击这里 网站运营推广招聘
IT PHP 编程语言 Linux 科技 开发编程 Elasticsearch HTML/CSS/XML 网络 JAVA NoSQL C/C++ 面试 Golang 数据库 Git 算法 正则表达式 操作系统 Redis 互联网 MySql JavaScript 运维 软件 架构设计 Mac OS TCP/IP 国际 Excel Vim Socket Windows Oracle VR MongoDB 运营 Python MemCache 商业 硬件 电子 设计 nginx 娱乐 摄影 游戏 WordPress HTTP 团建 数码电器
冷却塔厂家 广告
中文GPT4.0无需注册 广告
php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 [PHP] inet_pton/inet_ntop IP地址转换函数 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 PHPMailer设置utf8 PHPMailer字符集CharSet 如何在Composer中为GitLab实例设置访问令牌 array_multisort() 多字段排序 laravel框架查看sql语句方式 [原创]诡异的php-fpm超时问题 PHP获取指定函数定义在哪个文件中及行号 利用php soap实现web service php设置cookie为httponly防止xss攻击 PHP5 扩展SOAP 调用 webservice PHP-FPM进程数的设定 PHP7添加redis扩展 adodb手册 ADOConnection 公用函数 利用PHP SOAP实现WEB SERVICE php上周一、本周一、下周一日期 PHPstorm 里面Terminal 不能使用 esc键吗退出编辑模式吗
联系我们 半月雨文化 可降解耗材网 蓝云环保 生活百科 台州治疗白癜风医院 工程造价 78免费小説 上海网站seo优化 DDnovel 96小説 seo查询
北京半月雨文化科技有限公司.版权所有 京ICP备12026184号-3