how to execute postgresql function with unnest array as parameter using libpqxx c++

Question

I have created a postgresql function,

create or replace function check4(interval_ int[],password_ text[]) 
returns void as
$$
begin
     EXECUTE '
      INSERT INTO test(id,password)
      SELECT unnest($1),unnest($2)'
   USING $1,$2;  
end;
$$
language plpgsql;

Then i tried to execute the above procedure from c++ using libpqxx

try
    {
        connection *conn;
        conn = new connection("dbname = test user = postgres password = postgres hostaddr = 127.0.0.1 port = 5432");
        if (conn->is_open()) {
            cout<<"Opened database successfully:"<<std::endl<<std::flush;
        }
        else {
            cout << "Can't open database" << std::endl << std::flush;

        }

        int arr_id[2] = { 1,2 };
        string arr_pass[2] = { "hi","bye" };
        work P(*conn);
        conn->prepare("example", "select check4(UNNEST(:$1), UNNEST(:$2));");
            for (int i = 0; i < 2; i++)
            {
                P.prepared("example")(arr_id[i])(arr_pass[i]).exec();
            }

        P.commit();
        cout << "Records created successfully" << endl;

    }
    catch (const std::exception &e) {
        cerr << e.what() << std::endl;

    }

In this code, data is inserted one by one but i want the data to be inserted in bulk.I want to create array of 5000 records and insert in one shot.

Please anyone suggest me, How to pass array as parameter to a function? Any help appreciated.

Thank you.