如何将二进制补码二进制字符串转换为负十进制数？

Question

我正在尝试寻找一种 quick/easy 方法将二进制补码二进制字符串转换为负十进制数。我尝试使用 this question 中提供的方法，但它不起作用。这是我正在尝试的代码运行:

short res = (short)Integer.parseInt("1001", 2);
System.out.println(res);

当我运行这段代码结果是9。我错过了什么吗？我做错了什么？

Answer 1

When i run this code the result is 9.

理应如此。

Am i missing something? What am i doing wrong?

您的代码与您引用的答案之间的区别在于输入中的位数。 "Two's complement" 在没有指定宽度的情况下定义不明确。您复制的答案是 16 位二进制补码，因为 Java short 是 16 位宽。如果您想要 4 位二进制补码，则没有相应的 Java 数据类型，因此您将无法采用相同的快捷方式。

Answer 2

在 Two's Complement algorithm, 之后我写了以下内容：

public static int getTwosComplement(String binaryInt) {
    //Check if the number is negative.
    //We know it's negative if it starts with a 1
    if (binaryInt.charAt(0) == '1') {
        //Call our invert digits method
        String invertedInt = invertDigits(binaryInt);
        //Change this to decimal format.
        int decimalValue = Integer.parseInt(invertedInt, 2);
        //Add 1 to the curernt decimal and multiply it by -1
        //because we know it's a negative number
        decimalValue = (decimalValue + 1) * -1;
        //return the final result
        return decimalValue;
    } else {
        //Else we know it's a positive number, so just convert
        //the number to decimal base.
        return Integer.parseInt(binaryInt, 2);
    }
}

public static String invertDigits(String binaryInt) {
    String result = binaryInt;
    result = result.replace("0", " "); //temp replace 0s
    result = result.replace("1", "0"); //replace 1s with 0s
    result = result.replace(" ", "1"); //put the 1s back in
    return result;
}

以下是一些示例运行：

run:
Two's Complement of: 1000: -8
Two's Complement of: 1001: -7
Two's Complement of: 1010: -6
Two's Complement of: 0000: 0
Two's Complement of: 0001: 1
Two's Complement of: 0111: 7

如何将二进制补码二进制字符串转换为负十进制数？

how to convert twos complement binary string to negative decimal number?

java

binary

negative-number

twos-complement