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addcslashes

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

addcslashes — 以 C 语言风格使用反斜线转义字符串中的字符

说明

addcslashes(string $string, string $characters): string

返回字符串，该字符串在属于参数 characters 列表中的字符前都加上了反斜线。

参数

string

要转义的字符。

characters

如果 characters 中包含有 \n，\r 等字符，将以 C 语言风格转换，而其它非字母数字且 ASCII 码低于 32 以及高于 126 的字符均转换成使用八进制表示。

当定义 characters 参数中的字符序列时，需要确保知道设置为开始及结束范围之内的字符都是什么。

<?php
echo addcslashes('foo[ ]', 'A..z');
// 输出：\f\o\o\[ \]
// 所有大小写字母均被转义
// ... 但 [\]^_` 以及分隔符、换行符、回车符等也一并被转义了。
?>

另外，如果设置范围中的结束字符 ASCII 码高于开始字符，则不会创建范围，只是将开始字符、结束字符以及其间的字符逐个转义。可使用 ord() 函数获取字符的 ASCII 码值。

<?php
echo addcslashes("zoo['.']", 'z..A');
// 输出：\zoo['\.']
?>

当选择对字符 0，a，b，f，n，r，t 和 v 进行转义时需要小心。它们将被转换成 \0，\a，\b，\f，\n，\r，\t 和 \v，这些在 C 中都是预定义的转义序列。其中一些序列也在其它 C 派生语言（包含 PHP）中定义，这意味着如果使用 addcslashes() 和 characters 中定义的字符输出生成语言的代码，将不会得到预期的结果。

返回值

返回转义后的字符。

示例

characters 参数，如“\0..\37”，将转义所有 ASCII 码介于 0 和 31 之间的字符。

示例 #1 addcslashes() 例子

<?php
$escaped = addcslashes($not_escaped, "\0..\37!@\177..\377");
?>

参见

stripcslashes() - 反引用一个使用 addcslashes 转义的字符串
stripslashes() - 反引用一个引用字符串
addslashes() - 使用反斜线引用字符串
htmlspecialchars() - 将特殊字符转换为 HTML 实体
quotemeta() - 转义元字符集

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User Contributed Notes 6 notes

down

phpcoder at cyberpimp dot pimpdomain dot com ¶

18 years ago

If you are using addcslashes() to encode text which is to later be decoded back to it's original form, you MUST specify the backslash (\) character in charlist!

Example:

<?php
  $originaltext = 'This text does NOT contain \\n a new-line!';
  $encoded = addcslashes($originaltext, '\\');
  $decoded = stripcslashes($encoded);
  //$decoded now contains a copy of $originaltext with perfect integrity
  echo $decoded; //Display the sentence with it's literal \n intact
?>

If the '\\' was not specified in addcslashes(), any literal \n (or other C-style special character) sequences in $originaltext would pass through un-encoded, but then be decoded into control characters by stripcslashes() and the data would lose it's integrity through the encode-decode transaction.

down

stein at visibone dot com ¶

15 years ago

addcslashes() treats NUL as a string terminator:

   assert("any"  === addcslashes("any\0body", "-"));

unless you order it backslashified:

   assert("any\\000body" === addcslashes("any\0body", "\0"));

(Uncertain whether this should be declared a bug or simply that addcslashes() is not binary-safe, whatever that means.)

down

natNOSPAM at noworrie dot NO_SPAM dot com ¶

21 years ago

I have found the following to be much more appropriate code example:



<?php

$escaped = addcslashes($not_escaped, "\0..\37!@\@\177..\377");

?>



This will protect original, innocent backslashes from stripcslashes.

down

glitchmr at myopera dot com ¶

10 years ago

If you need JS escaping function, use json_encode() instead.

down

-3

vishal dot ceeng at gmail dot com ¶

4 years ago

echo addcslashes("zoo['.']", 'z..A');

Above code will create an error as per below
 
Invalid '..'-range, '..'-range needs to be incrementing -

down

-4

Johannes ¶

15 years ago

Be carefull with adding the \ to the list of encoded characters. When you add it at the last position it encodes all encoding slashes. I got a lot of \\\ by this mistake.

So always encode \ at first.

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