PHP escape string

Method 1： Manual escape 、 Restore string

Strings can be in single quotes ' '、 Double quotes " "、 delimiter <<<3 How to define , The simplest way is to use single quotation marks ' ' To define a string . When using strings , It is likely that these symbols that define the string will also be used as part of the string , To avoid confusion , It is necessary to use the transfer character in front of these symbols \.

\ It's an escape sign , Keep up with the \ The next first character will become a meaningless or special character . for example ,' Is a special symbol that defines a string , The written \' after , It loses its function of defining strings , It has become an ordinary single quotation mark . We can use echo "\'"; To output a single quotation mark , Escape character \ Will not show .

【 Example 】 Use escape words \ Escape a string .

<?php
header("Content-type:text/html;charset=utf-8");
echo 'Name：\'php Chinese net \'<br>Url：\'https://www.php.cn//\'';
?>

The operation results are as follows ：

For simple strings , It is recommended to use manual methods to escape strings , For strings with a large amount of data , It is suggested to use the automatic escape function to escape the string .

2、 Auto escape 、 Restore string

Auto escape 、 Restore string can be used PHP Provided addslashes() Functions and stripslashes() Function implementation .

addslashes() The function adds \, Escape the specified string , The syntax is as follows ：

addslashes($str)

addslashes() Function returns a string , For the needs of database query and other statements , Some characters will be preceded by a backslash , These characters are single quotes '、 Double quotes "、 Backslash \ And NULL.

stripslashes() The function restores an escaped string , That is to remove the backslash added to the string , The syntax is as follows ：

stripslashes($str)

stripslashes() Function will return a string after removing the escape backslash （\' Convert to ', Double backslash \\ Converted to a single backslash \）.

【 Example 】 Use addslashes() Function to escape a string , And then use stripslashes() Function to restore .

<?php
header("Content-type:text/html;charset=utf-8");
$sql = "select * from php where website='php Chinese net '";
$str = addslashes($sql);
echo $str.'<br>';
$str = stripslashes($str);
echo $str;
?>

The operation results are as follows ：