三条数据 判断其中最大与最小

/// <summary>
        /// 获取取大值
        /// </summary>
        /// <param name="a">P1值</param>
        /// <param name="b">P2值</param>
        /// <param name="c">P3值</param>
        /// <returns>float</returns>
        public float GetMaxValue(string a, string b, string c)
        {
            if (string.IsNullOrEmpty(a))
            {
                a = "0";
            }
            if (string.IsNullOrEmpty(b))
            {
                b = "0";
            }
            if (string.IsNullOrEmpty(c))
            {
                c = "0";
            }
            float A = Convert.ToSingle(a);
            float B = Convert.ToSingle(b);
            float C = Convert.ToSingle(c);
            return (A > B) ? (A > C ? A : C) : (B > C ? B : C);
        }
        /// <summary>
        /// 获取取小值
        /// </summary>
        /// <param name="a">P1值</param>
        /// <param name="b">P2值</param>
        /// <param name="c">P3值</param>
        /// <returns>float</returns>
        public float GetMinValue(string a, string b, string c)
        {
            if (string.IsNullOrEmpty(a))
            {
                a = "0";
            }
            if (string.IsNullOrEmpty(b))
            {
                b = "0";
            }
            if (string.IsNullOrEmpty(c))
            {
                c = "0";
            }
            float A = Convert.ToSingle(a);
            float B = Convert.ToSingle(b);
            float C = Convert.ToSingle(c);
            return (A < B) ? (A < C ? A : C) : (B < C ? B : C);
        }