爲什麼我的while循環被跳過？

Question

我想我的程序正在跳過我的while循環，但我實在不確定發生了什麼。該函數應該通過找到GCD然後再除以分子和分母來減少分數。

class Rational { 

private int numerator, denominator; 

//Constructor 
public Rational (int num, int den) { 
    numerator = num; 
    denominator = den; 
} 

//Method for multiplying fractions 
public Rational times (Rational that) { 
    Rational x = new Rational (this.numerator*that.numerator, this.denominator*that.denominator); 
    x = x.reduce(); 
    return x; 
} 

//Method for displaying fractions as strings 
public String toString() { 
    return new String(numerator+"/"+denominator); 
} 

//Method for adding fractions 
public Rational plus(Rational that) { 
    Rational x = new Rational ((this.numerator*that.denominator)+(that.numerator*this.denominator), 
      this.denominator*that.denominator); 
    //x = x.reduce(); 
    return x; 
} 

//Method for subtracting fractions 
public Rational minus(Rational that) { 
    Rational x = new Rational ((this.numerator*that.denominator)-(that.numerator*this.denominator), 
      this.denominator*that.denominator); 
    //x = x.reduce(); 
    return x; 
} 

//Method for dividing fractions 
public Rational divideBy(Rational that) { 
    Rational x = new Rational (this.numerator*that.denominator, this.denominator*that.numerator); 
    //x = x.reduce(); 
    return x; 
} 

public Rational reduce() { 
    int a = Math.abs(this.numerator); 
    int b = Math.abs(this.denominator); 
    int c = Math.min(a, b); 
    System.out.println(c); 
    System.out.println(a%c); 
    System.out.println(b%c); 
    if (a==0) { 
     return new Rational (0,1); 
    } 
    else { 
     while (((a%c)!= 0) && ((b%c)!= 0)) { 
      c = c-1; 
      System.out.println(c); 
     } 
     System.out.println(c); 
     return new Rational (this.numerator/c,this.denominator/c); 
    } 
} 
} 

public class RationalTester { 

public static void main(String[] args) { 
    Rational x = new Rational (6,4); //The fraction 6/4 
    Rational y = new Rational (5,2); //The fraction 5/2 
    Rational z = x.times(y); //Their product 
    Rational w = x.plus(y); //Their sum 
    Rational v = x.minus(y); //Their difference 
    Rational u = x.divideBy(y); //Their quotient 
    JOptionPane.showMessageDialog(null, x.toString()+" * "+y.toString()+" = "+z.toString()); 
    JOptionPane.showMessageDialog(null, x.toString()+" + "+y.toString()+" = "+w.toString()); 
    JOptionPane.showMessageDialog(null, x.toString()+" - "+y.toString()+" = "+v.toString()); 
    JOptionPane.showMessageDialog(null, x.toString()+"/"+y.toString()+" = "+u.toString()); 

} 

} 

我得到的分子和分母的絕對值，以確保如果分數是負的，我會保持，在年底。如果分子是0，我被要求返回（0,1）。問題是關於while循環......它似乎被完全跳過了。有什麼建議麼？

Answer 1

因爲它的條件總是錯誤的。

在第一行中設置c等於a或b。所以有兩種可能性：

• 如果c == a，則a%c將爲零。所以這個條件是錯誤的。
• 如果c == b，則b%c將爲零。所以這個條件是錯誤的。