Convert php characters to byte array

In PHP, you can use the str_split and unpack functions to convert characters to byte arrays. The following is the specific implementation method:

// 定义待转换的字符串
$str = "hello world";

// 使用 str_split 函数将字符串拆分为字符数组
$chars = str_split($str);

// 使用 unpack 函数将字符数组转换为字节数组
$bytes = unpack('C*', implode('', $chars));

// 输出字节数组
print_r($bytes);

In the above code, we first define the string to be converted, and then use the str_split function to split the string into a character array. Next, use the implode function to combine the character arrays into a string, and then use the unpack function to convert the string into a byte array. Finally, use the print_r function to output the byte array.

It should be noted that the first parameter of the unpack function is a format string, which is used to specify the data type and endianness of the byte array. In this example, we used the format string C*, where C represents the unsigned character type and * represents the use of the default endianness (usually the host byte order). If you need to specify the endianness, you can use the following format string:

• C: unsigned character type, occupying 1 byte;
• S: Unsigned short integer type, occupies 2 bytes;
• L: Unsigned long integer type, occupies 4 bytes;
• N: Unsigned long integer type, using network byte order, occupying 4 bytes;
• J: Unsigned long integer type, using local Endianness, occupies 8 bytes;
• Q: Unsigned long integer type, occupies 8 bytes;
• P : Pointer type, used to represent the value pointing to the memory address, occupying the same number of bytes as the number of machine pointers.

By using different format strings, we can convert various types of data into byte arrays to meet different needs.

In short, converting characters to byte arrays is very simple in PHP. You only need to use the str_split and unpack functions to complete. This conversion method is widely used in network programming, encryption and decryption, etc.

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