How to escape string in php

In PHP, string is a very common data type. When writing PHP code, we sometimes need to deal with some special characters, such as quotation marks, slashes, etc. These characters need to be escaped, otherwise they will cause syntax errors or security issues.

Escape means converting some special characters into corresponding escape characters. In PHP, we can use backslash (\) to escape meaning, such as escaping double quotes into \", escaping single quotes into \', escaping backslashes into \, etc.

The following are some common escape characters:

1. \n: Line feed character
2. \r: Carriage return character
3. \t: Tab Symbol
4. \": Double quotation mark
5. \': Single quotation mark
6. \: Backslash

In PHP, we can use Escape strings to escape some special characters into corresponding escape characters. For example:

$str1 = "He said, \"I'm fine.\"";
$str2 = 'It\'s a beautiful day.';
$str3 = 'C:\WINDOWS\system32\drivers\etc\hosts';
?>

In the above code, double quotes are used in $str1, so the double quotes need to be Quotation marks are escaped into \", while single quotes and slashes do not require additional processing. Single quotes are used in $str2, so single quotes need to be escaped into \', while double quotes and slashes do not require additional processing. Double slashes are used in $str3, so each slash needs to be escaped to \.

In addition to the above escape characters, PHP also provides some special character sequences, such as \U, \ u and \x, etc. These sequences are used to represent Unicode characters or ASCII codes and can be used in strings.

For example, the following code demonstrates how to use the \u and \x sequences to represent Unicode characters and ASCII Code:

echo "\u{2665}"; // Output❤️
echo "\x41"; // Output A
?>

In PHP, we can also use the stripslashes() function to remove backslashes in strings. For example:

$str = 'It\'s a beautiful day .';
echo stripslashes($str); // Output It's a beautiful day.
?>

In the above example, $str contains an escaped single quote, After using the stripslashes() function, the single quote is restored to its original state.

In short, in PHP, string escaping is a very basic skill, and we need to master some common escaping characters and special character sequences, and how to use escape functions to remove backslashes. Mastering this knowledge is crucial to writing high-quality and secure PHP code.

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