無論num1，num2或num3輸入的總分總是等於0.0

Question

此報價有何錯誤？它總是輸出0.0，而不是總比分結果

import java.util.Scanner; 

public class d { 

    public static void main(String[] args) { 

     Scanner input = new Scanner(System.in); 

     int num1; 
     int num2; 
     int num3; 
     int percentnum1; 
     int percentnum2; 
     int percentnum3; 
     double totalscore; 

     System.out.print("Enter paper 1 score (out of 90): "); 
     num1 = input.nextInt(); 

     System.out.print("Enter paper 2 score (out of 90): "); 
     num2 = input.nextInt(); 

     System.out.print("Enter IA score (out of 20): "); 
     num3 = input.nextInt(); 

     percentnum1 = (num1/90) * 100; 
     percentnum2 = (num2/90) * 100; 
     percentnum3 = (num3/20) * 80; 

     totalscore = (percentnum1 * 0.4) + (percentnum2 * 0.4) + (percentnum3 * 0.2); 

     System.out.println("The total score is " + totalscore); 


    } 
} 

Answer 1

好像下面的代碼引起的問題：如果的num1，num2和num3所有都值低於其分母

percentnum1 = (num1/90) * 100; 
percentnum2 = (num2/90) * 100; 
percentnum3 = (num3/20) * 80; 

結果（totalscore）將爲0.0，因爲整數除法，即使某些變量是90/90或20/20而其他變量小於分母，您w應該再次得到不正確的結果，並再次由於整數除法（雖然這次不一定是0.0）。

解決方法是簡單地使用double類型來保持精度。

double num1; 
double num2; 
double num3 
double percentnum1; 
double percentnum2; 
double percentnum3; 
double totalscore; 

Answer 2

變化int到doubleto avoid rounding down to 0。

Answer 3

如果您喜歡使用int類型，則可以先將數字相乘。希望它有幫助。

percentnum1 = num1 * 100/90; 
percentnum2 = num2 * 90/100; 
percentnum3 = num3 * 80/20;