.net 如果解析分数，如 1/4 ？

Question

string s="1/8"
double f = double.Parse(s);这样不行，因为是分数，不是浮点数。
难道就没有办法解析分数了吗？

Answer 1

public class Fraction
    {
        ulong divisor;
        ulong dividend;
        /// <summary>
        /// 分母
        /// </summary>
        public ulong Divisor
        {
            get
            {
                return divisor;
            }
            set
            {
                if (value != 0)
                    divisor = value;
                else
                    throw new Exception("分母不能为0.");
            }
        }        /// <summary>
        /// 分子
        /// </summary>
        public ulong Dividend
        {
            get
            {
                return dividend;
            }
            set
            {
                dividend = value;
            }        }        public double Value
        {
            get
            {
                return (double)Dividend / (double)Divisor;
            }
        }        public override string ToString()
        {
            return dividend.ToString() + "/" + divisor.ToString();
        }        /// <summary>
        /// 构造函数
        /// </summary>
        public Fraction() { }        /// <summary>
        /// 将string转成Fraction
        /// </summary>
        /// <param name="numberString">分数字符串</param>
        /// <returns> Fraction 实例，如果转换失败，返回null</returns>
        static public Fraction ConvertToFraction(string numberString)
        {
            if (string.IsNullOrEmpty(numberString))
                return null;
            string[] result = numberString.Split('/');
            if (result.Length != 2)
                return null;
            ulong divisor, dividend;
            try
            {
                divisor = Convert.ToUInt64(result[1]);
                dividend = Convert.ToUInt64(result[0]);
            }
            catch
            {
                return null;
            }
            if (divisor == 0)
                return null;            Fraction fraction = new Fraction();
            fraction.dividend = dividend;
            fraction.divisor = divisor;
            return fraction;        }        /// <summary>
        /// 加法
        /// </summary>
        /// <param name="fraction"></param>
        /// <returns></returns>
        public Fraction Add(Fraction fraction)
        {            Fraction result = new Fraction();
            result.Divisor = minCommonMultiple(this.Divisor, fraction.Divisor);
            result.Dividend = this.Dividend * result.Divisor / this.Divisor + fraction.Dividend * result.Divisor / fraction.Divisor;
            return Simplify(result);
        }        /// <summary>
        /// 减法
        /// </summary>
        /// <param name="fraction"></param>
        /// <returns></returns>
        public Fraction Subtract(Fraction fraction)
        {            Fraction result = new Fraction();
            result.Divisor = minCommonMultiple(this.Divisor, fraction.Divisor);
            result.Dividend = this.Dividend * result.Divisor / this.Divisor - fraction.Dividend *    result.Divisor / fraction.Divisor;
            return Simplify(result);
        }
        /// <summary>
        /// 乘法
        /// </summary>
        /// <param name="fraction"></param>
        /// <returns></returns>
        public Fraction Multiply(Fraction fraction)
        {
            Fraction result = new Fraction();
            result.Divisor = this.Divisor * fraction.Divisor;
            result.Dividend = this.Dividend * fraction.Dividend;
            return Simplify(result);
        }
        /// <summary>
        /// 除法
        /// </summary>
        /// <param name="fraction"></param>
        /// <returns></returns>
        public Fraction Divide(Fraction fraction)
        {
            Fraction result = new Fraction();
            result.Divisor = this.Divisor * fraction.Dividend;
            result.Dividend = this.Dividend * fraction.Divisor;
            return Simplify(result);
        }
        /// <summary>
        /// 最小公倍数
        /// </summary>
        /// <param name="num1"></param>
        /// <param name="num2"></param>
        /// <returns></returns>
        private static ulong minCommonMultiple(ulong num1, ulong num2)
        {
            ulong mcd = maxCommonDivisor(num1, num2);
            if (mcd == 1)
                return num1 * num2;
            return num1 * num2 / mcd;
        }        /// <summary>
        /// 最大公约数
        /// </summary>
        /// <param name="num1"></param>
        /// <param name="num2"></param>
        /// <returns></returns>
        private static ulong maxCommonDivisor(ulong num1, ulong num2)
        {            ulong min, max;
            if (num1 < num2)
            {
                min = num1;
                max = num2;
            }
            else
            {
                min = num2;
                max = num1;
            }
            double tmp = ((double)max / (double)min);
            ulong tmp2 = (ulong)tmp;
            if (tmp == (double)tmp2)
            {
                return tmp2;
            }
            return 1;
        }
        /// <summary>
        /// 化简
        /// </summary>
        /// <param name="fraction"></param>
        /// <returns></returns>
        static public Fraction Simplify(Fraction fraction)
        {
            ulong div = maxCommonDivisor(fraction.Divisor, fraction.Dividend);
            fraction.Divisor /= div;
            fraction.Dividend /= div;
            return fraction;
        }
    }

Answer 2

分数化小数
http://www.cnblogs.com/lsp/articles/623707.html

Answer 3

string s="1/8";
string[] strArray=s.Split('/');
double real=double.Parse(strArray[0])/double.Parse(strArray[1]);

Answer 4

string s="1/8"C#字符串中的/在数值型数据里是非法字符。所以格式不正确。
string s="1/8"
string[] tmp = s.Split('/');
double f = double.Parse(tmp[0])/double.Parse(tmp[1]);

Answer 5

string[] vtStr=s.Split(new char[]{'/'});double f;
if (vtStr==null||vtStr.Length<2)
{
    f=double.Parse(s);
}
else
{
    f=double.Parse(vtStr[0])/double.Parse(vtStr[1]);
}

Answer 6

'/'是除号，不是非法字符，不过5楼的这个写法是错的，
s.Split('/');Split没有char作为参数的版本吧？只有char[]参数，所以应该是s.Split(new char[]{'/'});