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使用数组将二进制转换为十进制

[英]Convert binary to decimal with an array

Im trying to make a binary string into a decimal. 我试图将二进制字符串转换为十进制。 It will terminate if -1 is entered. 如果输入-1,它将终止。 I am stuck with using an array. 我坚持使用数组。 It was suggested to use: public static int binaryToDecimal (String binaryString) . 建议使用:public static int binaryToDecimal(String binaryString)。 But Im not sure how to do that. 但是我不确定该怎么做。 This is what I have: 这就是我所拥有的:

import java.util.Scanner;

public class BinaryConversion {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        String inString;
        int decimal;

        System.out.println("Enter a binary number: ");
        inString = input.nextLine();

        while (inString != "-1") {
            int i;
            int binaryLength;

            binaryLength = inString.length();

            for (i = 0, decimal = 0; i < binaryLength; i++) {
                decimal = decimal * 2 + (inString[i] - 0);
                System.out.print(decimal);

            } 
            System.out.println("Enter a binary number: ");
            inString = input.nextLine();
        }
        System.out.println("All set !");
    }
}

It says there is a compilation problem with the array. 它说数组存在编译问题。 Thank you! 谢谢!

inString is a String, not an array. inString是字符串,而不是数组。 So, you can't use inString[i]. 因此,您不能使用inString [i]。 To get the character at a given position in the string, use inString.charAt(i), which returns a char. 要在字符串中的给定位置获取字符,请使用inString.charAt(i),它返回一个char。

Then, you'll also have to convert that char into an int. 然后,您还必须将该char转换为int。 You can do this with Character.getNumericValue(char). 您可以使用Character.getNumericValue(char)进行此操作。

So in summary, instead of 所以总的来说,

inString[i]

you need to use 你需要使用

Character.getNumericValue(inString.charAt(i))

Try this one: 试试这个:

        public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        String inString;
        int decimal;

        System.out.println("Enter a binary number: ");
        inString = input.nextLine();
        //Character.getNumericValue(inString.charAt(i))

        while (inString != "-1") {
            int i;
            int binaryLength;

            binaryLength = inString.length();

            for (i = 0, decimal = 0; i < binaryLength; i++)
            {
                decimal = decimal * 2 + (Character.getNumericValue(inString.charAt(i)) - 0);
                System.out.print(decimal);

            } 
            System.out.println("Enter a binary number: ");
            inString = input.nextLine();
        }
        System.out.println("All set !");
    }

} }

As suggested, you have to use Character.getNumericValue 根据建议,您必须使用Character.getNumericValue

You can simplify the code by using Integer.parseInt() : 您可以使用Integer.parseInt()简化代码:

public static void main(String[] args) {
    final Scanner input = new Scanner(System.in);

    String inString;

    while (true) {
        System.out.println("Enter a binary number: ");
        inString = input.nextLine();

        if (inString.equals("-1"))
            break;

        System.out.println(Integer.parseInt(inString, 2));
    }
    System.out.println("All set !");
}

You had few logical and few syntax errors. 您几乎没有逻辑错误和语法错误。

This is working code : 这是工作代码:

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

    String inString;
    int decimal;

    System.out.println("Enter a binary number: ");
    inString = input.nextLine();

    while (!"-1".equals(inString)) {
        int i;
        int binaryLength;

        binaryLength = inString.length();

        for (i = binaryLength-1, decimal = 0; i >= 0; i--) {
            if (inString.charAt(i) == '1') {
                decimal += Math.pow(2, binaryLength-i-1);
            }
        }
        System.out.println(decimal);

        System.out.println("Enter a binary number: ");
        inString = input.nextLine();
    }
    System.out.println("All set !");
}

Note that comparing String cannot be done with == , you have to use equals or compareTo methods. 请注意,不能使用==完成比较String,您必须使用equalscompareTo方法。

byte[] binary = {1,1,0,1};

int decimal = 0;
for(int i=binary.length-1, j=0; i>=0; i--, j++){
    decimal  += binary[i]*Math.pow(2, j);
}

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