How to convert file to byte array in PHP

PHP is a scripting language widely used in Internet development. Its excellent performance and easy-to-learn characteristics have made it a popular development language. During the development process, we often need to convert files into byte arrays to meet specific needs.

This article will introduce the method of converting files to byte arrays in PHP, and provide some practical code examples to facilitate developers to get started quickly.

1. Use the file_get_contents function

In PHP, you can use the file_get_contents function to easily read the file into a string type and then convert it into a byte array. The specific steps are as follows:

1. Use file_get_contents to read files

$file_path = 'file.txt';
$file_content = file_get_contents($file_path);

In the above code, $file_path is the file path, and $file_content is the read file content.

2. Convert the string into a byte array

$byte_array = unpack('C*', $file_content);

In the above code, The unpack function converts a string into a byte array. 'C' means unsigned characters, '' means matching all characters.

The complete code is as follows:

$file_path = 'file.txt';
$file_content = file_get_contents($file_path);
$byte_array = unpack('C*', $file_content);

Use the above code to convert the file into a byte array.

2. Use the fread function

In addition to using the file_get_contents function, we can also use the fread function to read the file as a byte array. The specific steps are as follows:

1. Use the fopen function to open the file handle

$file_path = 'file.txt';
$handle = fopen($file_path, ' rb');

In the above code, 'rb' means opening the file in binary mode to prevent unnecessary conversion when reading binary files.

2. Read the file content and convert it into a byte array

$byte_array = array();
while(!feof($handle)){

$byte = fread($handle, 1);
array_push($byte_array, ord($byte));

}
fclose($handle);

In the above code, the feof function determines whether the end of the file has been reached, and the fread function reads the binary data of the file and converts it into a character type Bytes, the ord function can return the ASCII code value of the character.

The complete code is as follows:

$file_path = 'file.txt';
$handle = fopen($file_path, 'rb');
$byte_array = array() ;
while(!feof($handle)){

$byte = fread($handle, 1);
array_push($byte_array, ord($byte));

}
fclose($handle);

Use the above code to read the file as a byte array.

3. Practical code examples

In actual development, we need to perform different operations on files, so different code implementations are required. Some practical code examples are provided below for developers' reference.

1. Calculate file hash value

$file_path = 'file.txt';
$file_content = file_get_contents($file_path);
$hash_value = hash('sha256', $file_content);

The above code uses the SHA-256 algorithm to calculate the hash value of the file. The hash function can conveniently perform hash calculations.

2. Get image file width and height information

$file_path = 'image.png';
$handle = fopen($file_path , 'rb');
$byte_array = array();
while(!feof($handle)){

$byte = fread($handle, 1);
array_push($byte_array, ord($byte));

}
fclose($handle);
$image_info = getimagesize($file_path) ;
$width = $image_info[0];
$height = $image_info[1];

The above code uses the getimagesize function in the PHP function library to easily obtain the width of the image file and height information.

3. Determine file type

$file_path = 'document.docx';
$finfo = new finfo(FILEINFO_MIME_TYPE);
$file_type = $finfo ->file($file_path);
if($file_type == 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'){

echo '该文件为Word文件';

}

Use the above code The finfo function in the PHP function library can easily obtain the MIME type information of the file to determine the file type.

4. Summary

This article introduces how to convert files into byte arrays in PHP, and provides some practical code examples for developers to refer to. In actual development, we need to choose according to specific needs and use appropriate methods for file conversion. At the same time, we can also use other PHP function libraries, such as SPL and Pattern, to implement file operations and processing.

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