A brief analysis of several ways to implement url encoding in PHP

With the popularity of the Internet, data transmission is becoming more and more common. In network communication, it is often necessary to convert some data into a form that can be recognized by the URL, which introduces the concept of URL encoding. The PHP language also has a rich built-in function library, which can play a big role in implementing URL encoding.

1. The concept of URL encoding

The full name of URL in English is Uniform Resource Locator (Uniform Resource Locator). It is the address that identifies resources on the Internet. It generally consists of protocol headers, domain names, paths, etc. . URL encoding is to encode the special characters of the URL into a recognizable form.

The URL encoding methods implemented in different languages ​​are different, but they all escape or replace special characters in the URL to avoid confusion with the address itself.

2. Common special characters in URL encoding

Common URL special characters are as follows:

1. Space: In the URL address, spaces will be encoded as " " (ASCII value is 0x20).
2. All characters except English letters and numbers: will be encoded into the format of "%xy", where xy is the hexadecimal representation of the character's ASCII code. For example: The ASCII code of the "%" character is 0x25, so in URL encoding, this character will be encoded as "%".
3. " " character: Like spaces, they will also be encoded as " ".

3. PHP’s URL encoding function

There are many URL encoding functions in PHP, such as urlencode(), rawurlencode(), urlencode() and http_build_query() and so on. Below, let’s take a look at their different ways of implementing URL encoding.

1. urlencode()

The urlencode() function is PHP’s built-in URL encoding function. It encodes the characters in the URL and replaces the special characters in the URL with specific strings (for example, " " represents a space, etc.).

The following is the syntax of the urlencode() function:

string urlencode ( string $str )

Description:

$str: The string that needs to be encoded.

The following is an example of using the urlencode() function:

<?php $str = "编码和解码 URL 中的字符串";
echo urlencode($str);
?>

Output result:

%E7%BC%96%E7%A0%81%E5%92%8C%E8%A7%A3%E7%A0%81%20URL%20%E4%B8%AD%E7%9A%84%E5%AD%97%E7%AC%A6%E4%B8%B2

2. rawurlencode()

rawurlencode( ) function is a built-in URL encoding method in PHP. Unlike the urlencode() function, it does not encode spaces. This function will encode all non-alphanumeric characters in the URL into the form %XX, where XX is the hexadecimal representation of the ASCII code of the character.

The following is the syntax of the rawurlencode() function:

string rawurlencode ( string $str )

Description:

$str: The string that needs to be encoded.

The following is an example of using the rawurlencode() function:

<?php $str = "编码和解码 URL 中的字符串";
echo rawurlencode($str);
?>

Output result:

%E7%BC%96%E7%A0%81%E5%92%8C%E8%A7%A3%E7%A0%81%20URL%20%E4%B8%AD%E7%9A%84%E5%AD%97%E7%AC%A6%E4%B8%B2

3. http_build_query()

http_build_query( ) function can encode an array according to URL encoding specifications and return the encoded string.

The following is the syntax of the http_build_query() function:

string http_build_query ( mixed $query_data [, string $numeric_prefix = NULL [, string $arg_separator = NULL [, int $enc_type = PHP_QUERY_RFC1738 ]]] )

Description:

$query_data: Array that needs to be encoded.

$numeric_prefix: The prefix for the array key. The default value is "null" with no prefix.

$arg_separator: The separator of the encoded string. The default is"&".

$enc_type: url encoding method. The default value is PHP_QUERY_RFC1738, which indicates the RFC1738 standard method for URL encoding.

The following is an example of using http_build_query():

<?php $data = array(
    &#39;name&#39; => 'Alice',
    'age' => 25,
    'address' => 'New York'
);
echo http_build_query($data);
?>

Output result:

name=Alice&age=25&address=New+York

The above are several ways to implement URL encoding in PHP, each with its own advantages and disadvantages, and according to Choose to use according to specific needs. For PHP developers, understanding these encoding methods and corresponding function libraries can make URL encoding easier.

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