是否有一种标准方法来乘以分数？

Question

我需要访问分母和分子，所以我不能只乘以两个浮点数。 我应该写我自己的类，并有运算符重载（*）或是他们已知的库提供吗？

Answer 1

恐怕你必须自己写。 Here是链接到的部分结构

代码的链接：

public struct Fraction 
{ 
    public int Numerator; 
    public int Denominator; 
    public static Fraction Zero = new Fraction(0, 0); 

    public Fraction(int numerator, int denominator) 
    { 
     this.Numerator = numerator; 
     this.Denominator = denominator; 

     //If denominator negative... 
     if (this.Denominator < 0) 
     { 
      //...move the negative up to the numerator 
      this.Numerator = -this.Numerator; 
      this.Denominator = -this.Denominator;       
     } 
    } 

    public Fraction(int numerator, Fraction denominator) 
    { 
     //divide the numerator by the denominator fraction 
     this = new Fraction(numerator, 1)/denominator; 
    } 

    public Fraction(Fraction numerator, int denominator) 
    { 
     //multiply the numerator fraction by 1 over the denominator 
     this = numerator * new Fraction(1, denominator); 
    } 

    public Fraction(Fraction fraction) 
    { 
     this.Numerator = fraction.Numerator; 
     this.Denominator = fraction.Denominator; 
    } 


    private static int getGCD(int a, int b) 
    { 
     //Drop negative signs 
     a = Math.Abs(a); 
     b = Math.Abs(b); 

     //Return the greatest common denominator between two integers 
     while (a != 0 && b != 0) 
     { 
      if (a > b) 
       a %= b; 
      else 
       b %= a; 
     } 

     if (a == 0) 
      return b; 
     else 
      return a; 
    } 

    private static int getLCD(int a, int b) 
    { 
     //Return the Least Common Denominator between two integers 
     return (a * b)/getGCD(a, b); 
    } 


    public Fraction ToDenominator(int targetDenominator) 
    { 
     //Multiply the fraction by a factor to make the denominator 
     //match the target denominator 
     Fraction modifiedFraction = this; 

     //Cannot reduce to smaller denominators 
     if (targetDenominator < this.Denominator) 
      return modifiedFraction; 

     //The target denominator must be a factor of the current denominator 
     if (targetDenominator % this.Denominator != 0) 
      return modifiedFraction; 

     if (this.Denominator != targetDenominator) 
     { 
      int factor = targetDenominator/this.Denominator; 
      modifiedFraction.Denominator = targetDenominator; 
      modifiedFraction.Numerator *= factor; 
     } 

     return modifiedFraction; 
    } 

    public Fraction GetReduced() 
    { 
     //Reduce the fraction to lowest terms 
     Fraction modifiedFraction = this; 

     //While the numerator and denominator share a greatest common denominator, 
     //keep dividing both by it 
     int gcd = 0; 
     while (Math.Abs(gcd = getGCD(modifiedFraction.Numerator, modifiedFraction.Denominator)) != 1) 
     { 
      modifiedFraction.Numerator /= gcd; 
      modifiedFraction.Denominator /= gcd; 
     } 

     //Make sure only a single negative sign is on the numerator 
     if (modifiedFraction.Denominator < 0) 
     { 
      modifiedFraction.Numerator = -this.Numerator; 
      modifiedFraction.Denominator = -this.Denominator; 
     } 

     return modifiedFraction; 
    } 

    public Fraction GetReciprocal() 
    { 
     //Flip the numerator and the denominator 
     return new Fraction(this.Denominator, this.Numerator); 
    } 


    public static Fraction operator +(Fraction fraction1, Fraction fraction2) 
    { 
     //Check if either fraction is zero 
     if (fraction1.Denominator == 0) 
      return fraction2; 
     else if (fraction2.Denominator == 0) 
      return fraction1; 

     //Get Least Common Denominator 
     int lcd = getLCD(fraction1.Denominator, fraction2.Denominator); 

     //Transform the fractions 
     fraction1 = fraction1.ToDenominator(lcd); 
     fraction2 = fraction2.ToDenominator(lcd); 

     //Return sum 
     return new Fraction(fraction1.Numerator + fraction2.Numerator, lcd).GetReduced(); 
    } 

    public static Fraction operator -(Fraction fraction1, Fraction fraction2) 
    { 
     //Get Least Common Denominator 
     int lcd = getLCD(fraction1.Denominator, fraction2.Denominator); 

     //Transform the fractions 
     fraction1 = fraction1.ToDenominator(lcd); 
     fraction2 = fraction2.ToDenominator(lcd); 

     //Return difference 
     return new Fraction(fraction1.Numerator - fraction2.Numerator, lcd).GetReduced(); 
    } 

    public static Fraction operator *(Fraction fraction1, Fraction fraction2) 
    { 
     int numerator = fraction1.Numerator * fraction2.Numerator; 
     int denomenator = fraction1.Denominator * fraction2.Denominator; 

     return new Fraction(numerator, denomenator).GetReduced(); 
    } 

    public static Fraction operator /(Fraction fraction1, Fraction fraction2) 
    { 
     return new Fraction(fraction1 * fraction2.GetReciprocal()).GetReduced(); 
    } 


    public double ToDouble() 
    { 
     return (double)this.Numerator/this.Denominator; 
    } 

    public override string ToString() 
    { 
     return Numerator + "/" + Denominator; 
    } 
} 

Answer 2

在c＃中没有准备好的类。编写自己的应该很容易。我会这样做。

Answer 3

谷歌是您的朋友：

http://www.codeproject.com/Articles/9078/Fraction-class-in-C

Answer 4

定义一个简单的对象将是对待一个简单的方法问题。

public class Fraction 
{ 
    decimal Denominator {get;set;} 
    decimal Numerator {get;set;} 

    public Fraction(decimal denum, decimal num) 
    { 
     Denominator = denum; 
     Numearator = num; 
    } 
    //this way you can instantiate a fraction object with any value of your choice 
} 

，只是后： 分数f =新分数（5，2）;