Question

所以我正在练习编写简单的Java程序。我做了一个将二进制数字更改为十进制。在所有if(){}之下的最后一个循环中，我的程序无缘无故跳到了别的地方。我已将这最后一个更改为另一个if语句和程序正常运行。但是我不知道第一个程序怎么可能跳转到其他程序。 if-else语句具有什么属性？

这是两个程序的代码和输出：

import java.util.Scanner;
public class NumberToBinary1 {

    public static void main(String[] args) {
        System.out.println("Put binary number: ");
        Scanner sn = new Scanner(System.in);
        String container = sn.nextLine();
        System.out.println(binaryToNumber(container));
   }

    private static double binaryToNumber(String container) {
        int numberLength = container.length();
        double result = 0;
        double power = 0;

        for (int i = numberLength-1; i >= 0; i--) {
            char a = container.charAt(i);
            int x =a;
            if (x == 49) {                          //if digit from binary number is 1 add 2^(number of power) to result
                result += java.lang.Math.pow(2d, power);
                power++;
            }
            if (x==48) {                            //if digit from binary number is 0, just skip to next power of 2
                power++;
            }
            else {
                System.out.println("issue with "+(i+1)+ " number"); //else give error with i+1th digit
            }
        }
        return result;
    }
}

输出：

Put binary number: 
10110105
issue with 8 digit
issue with 6 digit
issue with 4 digit
issue with 3 digit
issue with 1 digit
90.0

####第二：

import java.util.Scanner;

public class NumberToBinary1 {

    public static void main(String[] args) {
        System.out.println("Put binary number: ");
        Scanner sn = new Scanner(System.in);
        String container = sn.nextLine();
        System.out.println(binaryToNumber(container));
    }


    private static double binaryToNumber(String container) {
        int numberLength = container.length();
        double result = 0;
        double power = 0;

        for (int i = numberLength-1; i >= 0; i--) {
            char a = container.charAt(i);
            int x =a;
            if (x == 49) {                                  //if digit from binary number is 1 add 2^(number of power) to result
                result += java.lang.Math.pow(2d, power);
                power++;
            }
            if (x==48){                                     //if digit from binary number is 0, just skip to next power of 2
                power++;
            }
            if(x!=49 && x!=48) {System.out.println("issue with "+(i+1)+" digit"); //if digit from binary number is not 1 or 0 -> give error
            }
        }
        return result;
    }
}

输出：

Put binary number: 
10110105
issue with 8 digit
90.0

Answer 1

因为在您的第一个程序中else仅属于第二个if语句，这意味着所有未通过if的值都将转到else。在第二个程序中，您修改了语句。您也可以尝试将第一个程序修改为此，它应该会产生相同的结果：

private static double binaryToNumber(String container) {
    int numberLength = container.length();
    double result = 0;
    double power = 0;

    for (int i = numberLength-1; i >= 0; i--) {
        char a = container.charAt(i);
        int x =a;
        if (x == 49) {                          //if digit from binary number is 1 add 2^(number of power) to result
            result += java.lang.Math.pow(2d, power);
            power++;
        } else if (x==48) {                            //if digit from binary number is 0, just skip to next power of 2
            power++;
        } else {
            System.out.println("issue with "+(i+1)+ " number"); //else give error with i+1th digit
        }
    } return result;
}

其他问题（如果没有理由，请跳至其他程序）

1 个答案: