Using PHP's filesize() Function to Retrieve File Size

In PHP development, we often need to obtain file size information, and PHP provides a convenient function for this purpose— filesize() . The filesize() function is used to get the size of a specified file, returning the size in bytes. This article details the usage of the filesize() function and provides concrete code examples.

Usage:

The usage of filesize() is very simple. Below is its basic syntax:

<code>filesize(string $filename): int|false</code>

Here, $filename specifies the path of the file whose size is to be obtained. The function returns the file size, or false on failure.

Code Example:

Below is an actual code example showing how to use filesize() to get a file's size:

<code>$filename = 'file.txt';

// Check if the file exists
if (file_exists($filename)) {
    $filesize = filesize($filename);
    echo '文件 ' . $filename . ' 的大小为 ' . $filesize . ' 字节。';
} else {
    echo '文件 ' . $filename . ' 不存在。';
}
</code>

In the example, we first specify the file path, use file_exists() to check whether the file exists. If it exists, we call filesize() to obtain the size and print it; otherwise we print an appropriate error message.

Notes:

When using filesize() , keep the following points in mind:

filesize() only works for local files and does not support retrieving the size of network files.

To obtain the size of a network file, use other methods such as the cURL library or sending an HTTP HEAD request.

File size is returned in bytes; to convert it to more human‑readable units (e.g., KB, MB), simple calculations can be applied.

Conclusion:

The filesize() function is a convenient way in PHP to obtain file size information, providing a simple method for file operations. After reading this article, you should have a clearer understanding of how to use filesize() and be able to apply it flexibly in real development scenarios.

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