How Can I Efficiently Check File Extensions in PHP?

How to Effectively Check File Extensions Using PHP

File extension validation is crucial in ensuring secure file uploads. In PHP, the pathinfo() function provides a convenient way to extract file extensions. However, it's essential to optimize the validation process for efficiency.

Original Approach:

The provided code utilizes the pathinfo() function to extract the file extension and compares it against specific values to determine its validity:

$filename = $_FILES['video_file']['name'];
$ext = pathinfo($filename, PATHINFO_EXTENSION);
if ($ext !== 'gif' || $ext !== 'png' || $ext !== 'jpg') {
    echo 'error';
}

Potential Inefficiency:

However, this approach might not be efficient if a large number of allowed extensions exist. Checking each extension individually using multiple comparisons is computationally expensive.

Optimized Approach:

To improve efficiency, it's recommended to use an array to store the allowed file extensions:

$allowed = array('gif', 'png', 'jpg');
$filename = $_FILES['video_file']['name'];
$ext = pathinfo($filename, PATHINFO_EXTENSION);
if (!in_array($ext, $allowed)) {
    echo 'error';
}

This approach eliminates the need for multiple comparisons by using the in_array() function to check if the extension exists within the allowed extensions array. This significantly reduces the number of operations required and makes the validation process faster and more efficient.

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