How to escape string in php? A brief analysis of common methods

In PHP programming, some special characters need to be escaped when inputting strings to prevent the entered values ​​from causing program errors or posing security threats to the system. This article will introduce common string escape methods in PHP and provide readers with some practical examples.

1. addslashes() function

addslashes() function can escape single quotes, double quotes, backslashes and NUL characters contained in strings. The usage method is as follows:

$str = "I'm a PHP developer";
$str = addslashes($str);
echo $str;

The above code will escape the single quotes in the string, and the output result is: I\'m a PHP developer.

2. stripslashes() function

stripslashes() function is used to delete backslashes in strings. Its usage is as follows:

$str = "I\'m a PHP developer";
$str = stripslashes($str);
echo $str;

The above code deletes the backslashes in the original escaped string. The output result is: I'm a PHP developer.

3. htmlspecialchars() function

htmlspecialchars() function can convert some characters that need to be escaped, such as the greater than sign, less than sign, quotation marks, and symbols, etc., into HTML Output in the form of entities to avoid confusion in the web page structure or attacks on the system when the browser accesses the page. An example is as follows:

$str = "<p>Hello, world!</p>";
$str = htmlspecialchars($str);
echo $str;

The above code will escape angle brackets and symbols in the string, and the output result is:

Hello, world!

4. Mixed use of addslashes() and htmlspecialchars()

In practical applications, we usually mix the addslashes() and htmlspecialchars() functions to increase String security. The sample code is as follows:

$str = "<p>I'm a PHP developer</p>";
$str = addslashes($str);
$str = htmlspecialchars($str);
echo $str;

The above code first uses the addslashes() function to escape single quotes into \', and then uses the htmlspecialchars() function to escape angle brackets and symbols to ensure security.

Summary:

String escaping is very important in PHP programming. It prevents program errors and security issues from occurring. This article introduces common string escape methods in PHP and provides practical examples. I hope readers can master the relevant knowledge of string escape.

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