How does PHP read file content and convert it into binary data? What is the underlying principle?

In PHP, there are several ways to read file content and convert it to binary data, one of the common ways is to use file_get_contentsfunctions.

Here is a sample code that uses file_get_contentsa function to read the contents of a file and convert it to binary data:

$fileContent = file_get_contents('path/to/file');
$binaryData = unpack('H*', $fileContent)[1];

In the above code, file_get_contentsthe function is used to read the content of the file and store it in a variable $fileContent. Then, unpackthe file content is converted to binary data by a function and stored in a variable $binaryData.

The underlying principle is that file_get_contentsthe function reads the file content of the specified path into memory and returns a string. This string is actually a sequence of bytes containing the raw binary data of the file.

unpackThe function is used to unpack the string according to the specified format, thus converting it into binary data. In the example code, H*format is used, which means converting a string to a sequence of bytes represented in hexadecimal. This converts the file content into binary data and stores it in a variable for later use.

To summarize, it is possible to convert a file content to binary form in PHP by using file_get_contentsa function to read the file content, and a function to convert a string to binary data. unpackThe underlying principle is to convert the string to binary data by reading the file content into the memory, and then unpacking it according to the specified format.