不用循环，对数组每个元素进行处理，类型转换和输出

 double[] s0 = { 1, 2, 3 };

            //string[] s1= s.Cast<string>().ToArray();//必须为子类型，不存在类型转换
            string[] s1 = Array.ConvertAll(s0, delegate(double o) { return o.ToString(); });
            string[] s2 = Array.ConvertAll(s0, o => o.ToString());
            string s3 = string.Concat(s0);
            string s4 = string.Join(",", s0);
            double[] s5 = Array.ConvertAll(s0, o => o / s0.Sum());