What to do if php filesize() does not return correct results

PHP functionfilesize() is a very useful function that can return the size of a file. This function generally works fine in most cases. However, if you find that the filesize() method does not return the correct results in some cases, then you do not need to worry as this situation can be solved.

Next, let’s find out why filesize() does not return the correct result in some cases. At the same time, we will also share a few methods to solve this problem to ensure that your code can work properly.

Problem: PHP function filesize()Does not return correct results

In some cases, the filesize() method may return a Wrong file size value, which is caused by the following situations:

1. File path error

filesize()Function requirements You pass a correct file path to the file you want to retrieve the dimensions from. If you use an incorrect path, the function will not be able to find the file and will therefore return an error value. So before using the filesize() function, make sure you pass the correct file path.

2. The default return value of getFileSize()

If you are using a virtual host, you may see this problem under certain circumstances. In this case, you can try using the file_get_contents() function to get the size of the file. However, this method still does not work in all cases, because the method used by PHP when getting the file size depends on the server environment and PHP version. If you try the above method and still get an error, the problem may lie in the default return value of the getFileSize() function. The solution to this problem is to calculate the file size manually.

3. File encryption and protection

Some websites and servers will use encryption and protection to restrict access or even store files in different ways. At this time filesize()Cannot read the size of such files. This problem can be solved by asking the server to decrypt the file or provide a password.

4. File locking

If the file is being locked by another program, the filesize() function may be blocked. This usually happens when you have opened a file (such as writing to a log file) but have not closed the file handle. Make sure you close the file handle immediately and always after opening the file to avoid this problem.

Solution: Manually calculate the file size

If you find that filesize() does not return the correct results, you can try to manually calculate the file size. You can use PHP's fseek() and ftell() functions to get the distance between the current position and the end of the file. The following is a code example using this method:

function getFileSize($filename) {
    $handle = fopen($filename, "r");
    fseek($handle, 0, SEEK_END);
    $size_in_bytes = ftell($handle);
    fclose($handle);
    return $size_in_bytes;
}

In this code example, we open the file, move the file pointer to the end of the file, and use the ftell() function to get the end of the file position , and close the file handle. Finally, the file size is returned.

Summary:

Through this article, you should have understood why the filesize() method may not return the correct results in some cases. In the meantime, we've shared a few solutions to this problem to ensure your code works properly. When you encounter problems using filesize(), you can use the method of manually calculating the file size, or check whether factors such as file path, file locking and file encryption are causing filesize() The result is wrong.

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