邏輯錯誤 Java - BMI 計算錯誤

Question

該程序允許您輸入用戶的身高和體重，然后輸出 BMI 和相關的健康風險。 它將磅轉換為公斤。 它還將英尺和英寸的高度轉換為米。

    Scanner scanW = new Scanner (System.in);
    Scanner scanH = new Scanner (System.in);
    
    System.out.println("Enter your weight in pounds: ");
    int weight = scanW.nextInt();
    
    System.out.println("Enter your height in feet followed \nBy a space then additional inches");
    String height = scanH.nextLine();

    scanW.close();
    scanH.close();
    
    int heightFt = height.charAt(0);
    int heightInch = height.charAt(2);
    
    int finalHeightFeet = Integer.parseInt(String.valueOf(heightFt));
    int finalHeightInch = Integer.parseInt(String.valueOf(heightInch));
    
    double mass = (double) weight / 2.2;
    double finalHeight = (double) (finalHeightFeet * 0.3048) + (finalHeightInch * 0.0254);
    double BMI = (double) mass / (finalHeight * finalHeight);
    System.out.println("Your BMI is " +BMI);
    
    if (BMI < 18.5)
        System.out.println("Your risk category is UnderWeight");
    else if (BMI < 25)
        System.out.println("Your risk category is Normal Weight");
    else if (BMI < 30)
        System.out.println("Your risk category is Normal Overweight");
    else if (BMI >= 30)
        System.out.println("Your risk category is Obese");
    

正確的 BMI 和風險類別 output 應該是：

Your BMI is 25.013498117367398
Your risk category is Overweight.

但我的 output 會是這樣的：

Your BMI is 0.22261924276759873
Your risk category is UnderWeight

我很確定我的公式有問題，但我似乎找不到。 如果有人指出哪個是錯誤的，那將非常有幫助

Answer 1

您沒有正確解析高度輸入。

假設你輸入

5 9

作為高度。

您將“5 9”分配給height 。

然后你解析

int heightFt = height.charAt(0);
int heightInch = height.charAt(2);    

它將53分配給heightFt並將57分配給heightInch （這些是字符“5”和“9”的數值）。

試試這個：

String[] height = scanH.nextLine().split (" ");
int heightFt = Integer.parseInt (height[0]);
int heightInch = Integer.parseInt (height[1]);

Answer 2

您正在解析以數值表示的chars 。 看看ASCII TABLE 。

例如，如果您將6 2作為高度，則結果實際上是 6 為54 ，空間為32為50 。

Answer 3

scanW.close(); // these two are not necessary
scanH.close();

int heightInch = height.charAt(2); // what if the person is 5' 11" ?

我修改了你的代碼，看看。

Scanner scanW = new Scanner (System.in);
Scanner scanH = new Scanner (System.in);

System.out.println("Enter your weight in pounds: ");
int weight = scanW.nextInt();

System.out.println("Enter your height in feet followed \nBy a space then additional inches");
String height = scanH.nextLine();

int feets = Integer.parseInt(height.substring(0,1));

// get all the chars after index 2
int inches = Integer.parseInt(height.substring(2));

int totalInches = feets * 12 + inches;
double BMI = weight/Math.pow(totalInches, 2) * 703;
System.out.println("BMI: "+BMI);

Answer 4

System.out.println("Enter your weight in pounds: ");
    int weight = scan.nextInt();
    
    System.out.println("Enter your height in feet followed \nBy a space then additional inches");
    int heightFt = scan.nextInt();
    int heightInch = scan.nextInt();
    
    scan.close();
    
    double finalMass = weight / 2.2;
    double finalHeight = (heightFt * 0.3048) + (heightInch * 0.0254);
    double BMI = finalMass / (finalHeight * finalHeight);
    System.out.println("Your BMI is " +BMI);
    
    if (BMI < 18.5)
        System.out.println("Your risk category is UnderWeight");
    else if (BMI < 25 && BMI >= 18.5)
        System.out.println("Your risk category is Normal Weight");
    else if (BMI < 30 && BMI >= 25)
        System.out.println("Your risk category is Overweight");
    else
        System.out.println("Your risk category is Obese");