Java 寻找 1 的补码
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Finding 1's complement
提问by user2913004
I am trying to make a program to calculate 1's complement after entering a binary number. This is what I have to far:
我正在尝试编写一个程序来在输入二进制数后计算 1 的补码。这是我必须做的：
import java.util.Scanner;
public class BitWiseComplement {
public static void main(String[] args) {
Scanner keysIn = new Scanner(System.in);
System.out.println("Please enter your number: ");
long originalNum = keysIn.nextLong();
System.out.println(~originalNum);
}
}
However, when I enter 0111011, I get -111012. I thought the ~ operator was supposed to invert the number so that all 0s are 1s and all 1s are 0s.
但是，当我输入 0111011 时，我得到 -111012。我认为 ~ 运算符应该反转数字，以便所有 0 都是 1，所有 1 都是 0。
Any help?
有什么帮助吗？
采纳答案by arshajii
You presumably want to work in binary, so try:
你大概想在二进制中工作，所以尝试：
Scanner keysIn = new Scanner(System.in);
System.out.print("Please enter your number: ");
long originalNum = keysIn.nextLong(2); // specify radix of 2
System.out.println(Long.toBinaryString(~originalNum)); // print binary string
keysIn.close();
Please enter your number: 0111011 1111111111111111111111111111111111111111111111111111111111000100
As you can see, all bits are flipped. Bear in mind that there are leading 0s in front of the binary number you entered.
如您所见，所有位都被翻转。请记住，您输入的二进制数前面有前导 0。
回答by CmdrMoozy
The ~operator does what you think, but keep in mind that there are no unsigned types in Java, so when you enter a positive number (i.e., the high bit is a 0), applying ~to it will make it negative (by turning the high bit on).
该~运营商做什么，你想，但要记住，有没有无符号类型在Java中，所以当你输入一个正数（即高位为0），应用~到它将使负（通过关闭高有点）。
If you were to print the number out in hex (or binary, as other answers have suggested), you should see the answer you expect.
如果您要以十六进制（或二进制，正如其他答案所建议的那样）打印出数字，您应该会看到您期望的答案。
