可以通过以下方式将二进制转换为十进制：
var binary = "110";
var int = parseInt(binary, 2);
document.getElementById("results").innerHTML = int;<div id="results"></div>但是，我如何做相反的操作：将 int 转换为二进制？
let decimal = prompt('please insert decimal number');
console.log(Number(decimal).toString(2));/**
* Dec to Bin
* with bitwise operations
*
* Eudes Serpa M.
**/
const numberToConvert = 5;
const numberOfBits = 32; // 32-bits binary
const arrBitwise = [0]; // save the resulting bitwise
for (let i=0; i<numberOfBits; i++) {
let mask = 1;
const bit = numberToConvert & (mask << i); // And bitwise with left shift
if(bit === 0) {
arrBitwise[i] = 0;
} else {
arrBitwise[i] = 1;
}
}
const binary = arrBitwise.reverse().join("");
console.log(`This is the resulting binary: ${binary}`)
console.log(`This is the verification ${parseInt(binary, 2)}`);
说明：
第 2 行：我们指定组成生成的二进制文件的位数。
第 3 行：我们定义一个数组，用于保存位级操作产生的位。最后，这将是我们生成的二进制文件（反转它）
For：用于“创建”二进制位。
掩码：表示我们在位级别移位到的数字（1 进行 AND 运算并获得要转换的数字 1 中的位）。
bit：执行运算的结果位，例如：
位数 = 3;
掩码= 1；
for (i = 0 -> 31) { // 32 位
// Explanation of the operation to obtain the bit in position i
// ---- For i = 0;
1. mask << 0 = ...0001 (a 1 in decimal), since it does not do any shifting.
2. 3 & 1
/* At the bit level we have to
3 = ...0011
1 = ...0001,
so when doing the AND operation at the bit level, we have to:
0011
&0001
------
0001 === 1 decimal
*/
// bit then takes the value resulting from the previous operations. This is:
bit = 1;
// The if is not meet, so it enters the else:
arrBitwise[0] = 1;
// ---- For i = 1;
1. mask << 1 = ...0010 (a 2 in decimal)
2. 3 & 2
/* At the bit level we have to
3 = ...0011
2 = ...0010,
so when doing the AND operation at the bit level, we have to:
0011
&0010
-------
0010 === 2 decimal
*/
// bit then takes the value resulting from the previous operations. This is: bit = 2;
// The if is not meet, so it enters the else:
arrBitwise[1] = 1;
// ----- For i = 2;
1. mask << 2 = ...0100 (a 4 in decimal)
2. 3. 4
/* At the bit level we have to
3 = ...0011
4 = ...0100,
so when doing the AND operation at the bit level, we have to:
0011
&0100
-------
0000 === 0 decimal
*/
// bit then takes the value resulting from the previous operations. This is:
bit = 0;
// The if meet, so:
arrBitwise[2] = 0;
}
因此，arrBitwise 将是： arr按位 = [1, 1, 0, 0, ..., 0];
arrBitwise.reverse() // [0, ..., 0, 0, 1, 1]
与.join()
"0...0011"
用二进制表示3。
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_AND
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Left_shift
二进制和十进制都是具有不同基数的数字的字符串表示形式。
这就是为什么我们在从字符串获取数字时需要指定基数：
binary = '10101'
decimal = '21'
Number.parseInt(binary, 2) === Number.parseInt(decimal, 10) // true
同样，当我们将数字转换为字符串时，我们可以（但不必）指定基数：
n = 21
n.toString(2) // '10101'
Radix 在这里是可选的，省略时等于 10：
n = 21
n.toString() // '21'
请参阅 Number.prototype.toString() 了解更多详细信息。
您可以尝试使用无符号右移运算符。
>>> 0您可以运行下面的代码片段（如果尝试使用-6，输出应为 11111111111111111111111111111010）。
//Here you can test it directly
var number = -6;
alert((number >>> 0).toString(2));
//Or you can do it with a function
function dec2Bin(dec) {
return (dec >>> 0).toString(2);
}
alert(dec2Bin(-6));var x = 6;
console.log(x.toString(2));代码在注释中有解释
const input = 18;
const converted = deciToBinary(18, '') // function to convert decimal to binary
const countOnes = countOne(converted); // function to count the occurence of 1s
console.log(countOnes);
function countOne(input) {
const strlen = input.length;
let count = 0;
for (let i = 0; i < strlen; i++) {
if (parseInt(input[i])) {
count++
}
}
return count;
}
function deciToBinary(input, output) {
const reminder = input % 2; // find the reminder
const quotient = parseInt(input / 2); // find the quotient
if (quotient > 1) { // if quotient is > 1 i.e not 0 or 1
output += reminder; // add the reminder to the string
return deciToBinary(quotient, output); // using recursive function concept, recall the function
}
output += reminder; // add the reminder
output += quotient; // add the quotient
const binary = output.split('').reverse().join(''); // reverse the string
return binary;
}