The difference between characters and bytes in PHP and detailed explanation of string and byte conversion

Characters in php are abstract entities that can be represented using a variety of different character schemes or code pages. A byte is a unit for transmitting information over a network (or storing information on a hard drive or in memory). This article also introduces examples of string and byte conversion in PHP through examples. Friends who are interested should take a look together

Characters:

Characters are abstract entities that can be represented using many different character schemes or code pages. For example, Unicode UTF-16 encoding represents characters as a sequence of 16-bit integers, while Unicode UTF-8 encoding represents the same characters as a sequence of 8-bit bytes. The common language runtime uses Unicode UTF-16 (Unicode Transformation Format, a 16-bit encoding) to represent characters.

In php, under UTF-8 encoding, a Chinese character occupies 3 characters, and under gbk encoding, it only occupies 2 characters.

Byte (Byte):

Byte is to transmit information through the network (or store information on the hard disk or memory) The unit.

Application:

If the table in the database is UTF8 encoded, and the field is set to a maximum of 10 characters, the maximum storage length is eg: 'I am in 1'

Let’s look at the PHP string and byte conversion example

> 8 & 0xff); 
$byt[2] = ($val >> 16 & 0xff); 
$byt[3] = ($val >> 24 & 0xff); 
return $byt; 
} 
/** 
* 从字节数组中指定的位置读取一个Integer类型的数据 
* @param $bytes 字节数组 
* @param $position 指定的开始位置 
* @return 一个Integer类型的数据 
*/
public static function bytesToInteger($bytes, $position) { 
$val = 0; 
$val = $bytes[$position + 3] & 0xff; 
$val <<= 8; 
$val |= $bytes[$position + 2] & 0xff; 
$val <<= 8; 
$val |= $bytes[$position + 1] & 0xff; 
$val <<= 8; 
$val |= $bytes[$position] & 0xff; 
return $val; 
} 
/** 
* 转换一个shor字符串为byte数组 
* @param $byt 目标byte数组 
* @param $val 需要转换的字符串 
* 
*/
public static function shortToBytes($val) { 
$byt = array(); 
$byt[0] = ($val & 0xff); 
$byt[1] = ($val >> 8 & 0xff); 
return $byt; 
} 
/** 
* 从字节数组中指定的位置读取一个Short类型的数据。 
* @param $bytes 字节数组 
* @param $position 指定的开始位置 
* @return 一个Short类型的数据 
*/
public static function bytesToShort($bytes, $position) { 
$val = 0; 
$val = $bytes[$position + 1] & 0xFF; 
$val = $val << 8; 
$val |= $bytes[$position] & 0xFF; 
return $val; 
} 
} 
?>

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

Related recommendations:

PHP Gets the image width, height, size, image type, img attribute used for layout

# #7 ways to use PHP header()

PHP namespace (namespace)

The above is the detailed content of The difference between characters and bytes in PHP and detailed explanation of string and byte conversion. For more information, please follow other related articles on the PHP Chinese website!