What are the best practices for manipulating external content with PHP include and str_replace functions?

When manipulating external content with PHP include and str_replace functions, it is important to ensure that the external content is properly sanitized to prevent security vulnerabilities such as code injection. One good practice is to use PHP's file_get_contents function to retrieve the external content and then apply any necessary sanitization techniques, such as validating and filtering the content, before using str_replace to manipulate it.

// Retrieve external content
$external_content = file_get_contents('https://example.com/external-content');

// Sanitize the content
$filtered_content = filter_var($external_content, FILTER_SANITIZE_STRING);

// Manipulate the content using str_replace
$manipulated_content = str_replace('old_string', 'new_string', $filtered_content);

// Output the manipulated content
echo $manipulated_content;