What are common pitfalls for beginners when trying to save user input as a file in PHP?

One common pitfall for beginners when trying to save user input as a file in PHP is not properly sanitizing the input, which can lead to security vulnerabilities such as code injection. To solve this issue, always sanitize user input before saving it to a file by using functions like htmlspecialchars() or htmlentities(). Additionally, make sure to validate the input to ensure it meets any necessary criteria before saving it. 

// Sanitize user input before saving it to a file
$userInput = htmlspecialchars($_POST['user_input']);

// Validate the input before saving it to a file
if(strlen($userInput) > 0) {
    $file = fopen("user_input.txt", "w");
    fwrite($file, $userInput);
    fclose($file);
    echo "User input saved successfully!";
} else {
    echo "Invalid user input.";
}

Keywords

file handling user input security vulnerabilities error handling fopen

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