JavaScript的十进制二进制 - 64位 [英] Javascript Decimal to Binary - 64 bit

问题描述

有关小数-805306368二进制是：

The binary for the decimal -805306368 is:

11111111111111111111111111111111 11010000000000000000000000000000

11111111111111111111111111111111 11010000000000000000000000000000

然而，在Javascript中我得到的以下：

However, in Javascript I get the following:

   var str = parseInt(-805306368).toString(2);
   document.write(str);

-110000000000000000000000000000

-110000000000000000000000000000

谁能解释如何解析从这个十进制64位二进制字符串？

Can anyone explain how to parse the 64 bit binary string from this decimal?

推荐答案

JavaScript不使用二进制补码再presentation，它使用了 - 在字符字符串的前面。这是因为它不知道你的电话号码范围内有多少位了。

JavaScript does not use the two's-complement representation, it uses a - character in front of the string. That's because it does not know how many bits your number range has.

要获得期望的结果，你可以反转每个位：

To get the expected result, you could invert each bit:

>>> (~-805306368).toString(2)
"101111111111111111111111111111"

然而，JavaScript并在32位整数的所有二进制运算，所以这不会更大或更小的数字工作，至少会很混乱。所以，你需要实现自己的格式化算法。

Yet, javascript does all binary operations on 32-bit integers, so this won't work for bigger (or smaller) numbers and at least will be very confusing. So, you would need to implement your own formatting algorithm.

// example of to 32-bit-conversion:
>>> (~parseInt("1111111111111111111111111111111",2)).toString(2)
"-10000000000000000000000000000000"
>>> (~parseInt("11111111111111111111111111111111",2)).toString(2)
"0"

我的实现：

String.prototype.padleft = function(len, chr){...}

function get64binary(int) {
    if (int>=0)
        return int
          .toString(2)
          .padleft(64, "0");
    // else
    return (-int-1)
      .toString(2)
      .replace(/[01]/g, function(d){return +!+d;}) // hehe: inverts each char
      .padleft(64, "1");
}

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