How to calculate file size in php

For those who are new to PHP, it may be difficult to implement the function of getting the file size in PHP. However, I believe that novices will be able to easily master the important knowledge of obtaining file size with PHP after reading the introduction in this article!

Below we use specific code examples to provide you with a detailed analysis of how PHP obtains the file size.

1. First, if you only need to get the number of bytes of the file

You can get it directly through the PHP filesize function, the code is as follows:

echo filesize("upload.php");

Accessed through the browser, the output result is as follows:

As you can see from the above figure, the file size we obtain by direct output is 1614 bytes, while in upload. The file size seen in the php properties is 1614 bytes. We all know the file size. In addition to being expressed in bytes, it is more commonly expressed in units such as KB, MB, GB, and TB.

2. So if we want to get the file size and display it in a normal size format, how should we do it?

Below we introduce a very simple encapsulation method to obtain the normal size.

The specific code example of the PHP encapsulation method to obtain the normal size is as follows:

<?php
$size = filesize("upload.php");
function trans_byte($byte)
{
    $KB = 1024;
    $MB = 1024 * $KB;
    $GB = 1024 * $MB;
    $TB = 1024 * $GB;
    if ($byte < $KB) {
        return $byte . "B";
    } elseif ($byte < $MB) {
        return round($byte / $KB, 2) . "KB";
    } elseif ($byte < $GB) {
        return round($byte / $MB, 2) . "MB";
    } elseif ($byte < $TB) {
        return round($byte / $GB, 2) . "GB";
    } else {
        return round($byte / $TB, 2) . "TB";
    }
}
echo trans_byte($size);

In this code, we first define a $size variable to obtain the byte size of the upload.php file. Then create a method named filesize, which is used to convert the byte size into a normal size format.

Everyone should know that computer counting uses binary, which is calculated by powers of 2. 1KB=2 to the 10th power=1024B; 1MB=2 to the 20th power=1024*1024B=1024KB; GB, TB conversion and so on.

So in the filesize method, we first define the four variables $KB, $MB, $GB, and $TB in the above code. Then use if...elseif conditional statements to gradually determine the file byte size, and use the PHP round function to retain two decimal places on the file size value.

Then we test the above encapsulated filesize method to obtain the normal size of the file. Access php through the browser to obtain the file size. The result is as shown below:

From the above As can be seen from the figure, through our own encapsulated filesize method, we can already realize the function of PHP calculating the file size and successfully obtaining the normal size of the file. Some friends may have discovered that the obtained size is not exactly the same as the size of the file's own attributes. In fact, it is very normal to have a slight error when obtaining the size through the PHP method and can be ignored.

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