public class getpass : MonoBehaviour {

    public Text mes;
    public InputField field;
    public string mypass;

    void Start()
    {

        mes.text = "";
        mypass = "";

    }

    public void CodeOut()
    {

        mypass = field.text;
        field.text = "";

        StreamWriter sw = new StreamWriter(Application.dataPath + "/" + "testfile2.txt",false);

        sw.WriteLine(mypass);
        sw.Flush();
        sw.Close();

        mes.text = "※登録が完了しました";

    }
}