Binary file reading and writing operations in PHP

PHP is a language widely used in Web development. It provides many functions and methods for processing files. In PHP, we can use binary mode to read and write files. This method can improve the efficiency of file operations, especially when processing binary files. In this article, we will explore binary file reading and writing operations in PHP and how to use this method to process binary files.

What is a binary file?

Binary files refer to files represented by pure binary. The content may contain different encoded character sets, or the file may contain a large amount of binary data, such as images, audio, video and other files. In contrast, text files are files that store characters in line units, with each line ending in a newline character and stored using a specific character encoding.

Binary files are often used to store media files and program files such as images, sounds, and videos. The contents of these files need to be stored in binary form instead of character form.

How to read and write binary files in PHP?

In PHP, we can use the fopen() and fread() functions to open and read a binary file. The following is a simple sample code:

$file = fopen("file.bin", "rb");
$bytes = fread($file, filesize("file.bin"));
fclose($file);

The above code is used to open a file named "file.bin" in binary mode, read all the data in the file, and store it in a file named $bytes in the variables. Finally, use the fclose() function to close the file.

In the above sample code, we should note that when using the fopen() function to open a file, the second parameter "rb" means opening the file in binary read-only mode. Similarly, we can also use the fwrite() function to write data to a binary file. Here is a sample code:

$file = fopen("file.bin", "wb");
fwrite($file, $bytes);
fclose($file);

The above code is used to open a file named "file.bin" in binary mode, write the contents of a variable named $bytes into the file, and finally, use fclose () function closes the file.

It should be noted that when processing binary files, we must use binary mode to open, read and write files, otherwise incompatibility problems will occur.

How to deal with binary files?

When we need to process binary files, we usually need to understand the format, structure and content of the file. Before processing a file, we need to study it using documents such as file format specifications to know the type, order, and length of the information contained in the file. After that, we need to understand the byte order and how various data types are stored, such as integers, floating point numbers, characters, etc.

When processing binary files, we usually need to use some binary conversion functions, such as pack() and unpack() functions. The pack() function is used to convert PHP data to binary format, while the unpack() function is used to convert binary format to PHP data. Here is a sample code:

$int = 1234;
$bytes = pack("n", $int);

The above code is used to convert the integer 1234 into binary format and store it into a variable named $bytes. In this example, we use "n" to represent the binary format of an unsigned short.

The following is a reverse example:

$int = unpack("n", $bytes)[1];

The above code is used to convert the binary data named $bytes into a PHP integer and store it in a variable named $int. In this example, we use "n" to indicate that the binary data is in the format of an unsigned short.

When processing binary files, our task is to convert different data types to facilitate reading and writing the data in the file. You can use the pack() and unpack() functions to convert between data types and binary formats.

Summary

In this article, we explored binary file reading and writing operations in PHP, and what you need to know when working with binary files. We learned about the concept of binary files and how to use binary mode to read and write files. At the same time, we also learned how to handle binary files, that is, how to convert between PHP data types and binary formats by using the pack() and unpack() functions.

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