System.Json.JsonValue.DoEscapeString C# (CSharp) Method

        private static string DoEscapeString(StringBuilder sb, string src, int cur)
        {
            int start = cur;
            for (int i = cur; i < src.Length; i++)
                if (NeedEscape(src, i))
                {
                    sb.Append(src, start, i - start);
                    switch (src[i])
                    {
                        case '\b': sb.Append("\\b"); break;
                        case '\f': sb.Append("\\f"); break;
                        case '\n': sb.Append("\\n"); break;
                        case '\r': sb.Append("\\r"); break;
                        case '\t': sb.Append("\\t"); break;
                        case '\"': sb.Append("\\\""); break;
                        case '\\': sb.Append("\\\\"); break;
                        case '/': sb.Append("\\/"); break;
                        default:
                            sb.Append("\\u");
                            sb.Append(((int)src[i]).ToString("x04"));
                            break;
                    }
                    start = i + 1;
                }
            sb.Append(src, start, src.Length - start);
            return sb.ToString();
        }