How can one prevent errors when handling file access in PHP, especially when dealing with external sources?

To prevent errors when handling file access in PHP, especially when dealing with external sources, it is important to validate and sanitize user input, check for file existence before attempting to access it, handle exceptions properly, and use secure protocols when working with external sources. 

// Example of preventing errors when handling file access in PHP

// Validate and sanitize user input
$filename = filter_var($_POST['filename'], FILTER_SANITIZE_STRING);

// Check for file existence before attempting to access it
if (file_exists($filename)) {
    // Handle file access operation
    $fileContent = file_get_contents($filename);
    echo $fileContent;
} else {
    echo "File does not exist.";
}

Keywords

file access error handling PHP external sources exception handling

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