How can PHP developers optimize their code for displaying uploaded files, especially when dealing with form submissions and data processing?

When displaying uploaded files in PHP, developers can optimize their code by ensuring proper validation of file types, securely storing files, and efficiently processing form submissions. One way to achieve this is by using PHP's built-in file handling functions and validating file extensions before processing them. 

<?php
// Check if a file has been uploaded
if(isset($_FILES['file'])){
    $file = $_FILES['file'];

    // Validate file type
    $allowed_extensions = array('jpg', 'jpeg', 'png', 'gif');
    $file_extension = pathinfo($file['name'], PATHINFO_EXTENSION);
    
    if(!in_array($file_extension, $allowed_extensions)){
        echo "Invalid file type. Allowed types: jpg, jpeg, png, gif";
    } else {
        // Securely store the file
        $upload_dir = 'uploads/';
        $upload_file = $upload_dir . basename($file['name']);
        
        if(move_uploaded_file($file['tmp_name'], $upload_file)){
            echo "File uploaded successfully.";
        } else {
            echo "Error uploading file.";
        }
    }
}
?>

Keywords

file upload form submissions data processing optimization PHP functions

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