Encoding and conversion methods supported by PHP

PHP is a scripting language that is widely used in Web development, especially server-side program development. In the Web development process, encoding issues are a very important part. To solve encoding problems, you need to master the encoding and conversion methods supported by PHP. This article will introduce the main encoding types and conversion methods supported by PHP.

1. Encoding type

In the process of Web development, the commonly used encoding types are as follows:

1. ASCII encoding

The ASCII code is The American Standard Code for Information Interchange can represent 127 characters, including numbers, letters, and some special symbols. ASCII encoding is the earliest character set and is widely used in computer systems and communications fields.

2. ISO-8859 encoding

ISO-8859 encoding is a single-byte encoding that contains multiple character sets. Mainly used in European countries, it can represent all Latin letters, Cyrillic letters, Greek letters and a small number of non-Latin letters.

3. Unicode encoding

Unicode encoding is a standard character set that contains characters used in almost all modern languages. Unicode uses a 32-bit encoding and can represent more than 1 million characters. Unicode is divided into encoding formats such as UTF-8, UTF-16 and UTF-32. In web development, UTF-8 is the most commonly used Unicode encoding format.

4. GBK encoding

GBK encoding is an encoding developed in China and applied to Chinese characters. It is a double-byte encoding, and one Chinese character occupies two bytes. Compared with GB2312, GBK supports more Chinese characters.

2. Encoding conversion method

In web development, it is often necessary to encode strings. PHP provides the following encoding conversion methods:

1. iconv() function

iconv() function is one of the most commonly used encoding conversion functions in PHP. This function can convert a string in one character set into a string in another character set. It is usually used to convert UTF-8 encoded strings into other encodings such as GB2312, GBK or ISO-8859.

Syntax

string iconv ( string $input_charset , string $output_charset , string $str )

Parameter description

• input_charset: The original encoding format of the string to be converted.
• output_charset: The target encoding format to be converted to.
• str: ​​The string to be encoded and converted.

Example

$str = '这是一个UTF-8编码字符串';
$str_gb = iconv('UTF-8', 'GBK', $str);
echo $str_gb;  //输出：这是一个GBK编码字符串

2. mb_convert_encoding() function

The mb_convert_encoding() function can also implement string encoding conversion, similar to the iconv() function. The difference is that the mb_convert_encoding() function is usually used to process multi-byte characters and supports more encoding formats.

Syntax

string mb_convert_encoding ( string $str , string $to_encoding [, mixed $from_encoding = mb_internal_encoding() ] )

Parameter description

• str: ​​The string to be encoded and converted.
• to_encoding: The target encoding format to be converted to.
• from_encoding: The original encoding format of the string to be converted. If this parameter is not specified, the internal encoding returned by the mb_internal_encoding() function is used.

Example

$str = '这是一个UTF-8编码字符串';
$str_gb = mb_convert_encoding($str, 'GBK', 'UTF-8');
echo $str_gb;  //输出：这是一个GBK编码字符串

3. urlencode() function and urldecode() function

The urlencode() function can URL-encode a string and convert the string into Convert special characters into a format acceptable for the URL. The urldecode() function can decode the URL-encoded string and restore the URL-encoded characters to the original characters.

urlencode() function

string urlencode ( string $str )

Parameter description

• str: ​​The string to be URL encoded.

Example

$str = 'http://www.example.com/你好.php?name=小明';
$str_url = urlencode($str);
echo $str_url;  //输出：http%3A%2F%2Fwww.example.com%2F%E4%BD%A0%E5%A5%BD.php%3Fname%3D%E5%B0%8F%E6%98%8E

urldecode() function

string urldecode ( string $str )

Parameter description

• str: ​​String to be URL decoded.

Example

$str = 'http%3A%2F%2Fwww.example.com%2F%E4%BD%A0%E5%A5%BD.php%3Fname%3D%E5%B0%8F%E6%98%8E';
$str_decoded = urldecode($str);
echo $str_decoded;  //输出：http://www.example.com/你好.php?name=小明

3. Summary

Encoding issues are a very important part of web development. Incorrect encoding will lead to problems such as garbled code and failure to display. PHP provides a variety of encoding conversion methods, and you can choose the appropriate method to achieve encoding conversion according to your needs.

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