php convert string to byte array

In PHP programming, sometimes we need to convert a string into a byte array to facilitate binary data processing. In this article, we will explain how to convert a string into a byte array using PHP.

1. Use str_split() function

PHP’s str_split() function can split a string into an array, where each element is a single character (ASCII code). When using this function, you need to pay attention to character encoding issues. For example, if the string is UTF-8 encoded, each Chinese character typically requires 3 bytes or more of storage space.

The following is a sample code:

// 定义一个字符串
$str = 'hello world';

// 将字符串转换为字节数组
$bytes = array_map('ord', str_split($str));

In the above code, we first define a string ("hello world"), and then use the str_split() function to split it into an array. Next, we use PHP's built-in ord() function to convert each character to ASCII code, and store the converted array in the $bytes variable.

2. Use the unpack() function

PHP’s unpack() function can unpack binary data into an array or associative array in a specified format. This function is relatively powerful and can support unpacking in multiple formats, such as structures in C language, etc.

The following is a sample code:

// 定义一个字符串
$str = 'hello world';

// 将字符串转换为字节数组
$bytes = unpack('C*', $str);

In the above code, we first define a string ("hello world"), and then use the unpack() function to unpack it into C language character type ('C'). Finally, the converted byte array is stored in the $bytes variable.

3. Use the mb_str_split() function

If the string is a multi-byte encoding (such as UTF-8), the above method may produce wrong results because of the multi-byte Section characters need to be split according to their encoding format.

To solve this problem, you can use the mb_str_split() function to process multi-byte strings. This function is similar to the str_split() function, but supports multi-byte characters.

The following is a sample code:

// 定义一个多字节字符串
$str = '今天天气真好';

// 将字符串转换为字节数组
$bytes = array_map('ord', mb_str_split($str));

In the above code, we first define a multi-byte string ("The weather is really nice today"), and then use the mb_str_split() function to split it Split into multiple characters, and finally use the ord() function to convert each character into ASCII code, and store the converted array in the $bytes variable.

Summary

In PHP programming, when you need to convert a string into a byte array, you can use methods such as str_split(), unpack() or mb_str_split() functions. Among them, choosing the appropriate method needs to take into account many factors such as the encoding format of the string and the format of the binary data. In actual development, it is necessary to choose an appropriate method based on specific needs.

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