Exploring the JavaScript Bitwise NOT Operator and the toString() Method

Question

Exploring the JavaScript Bitwise NOT Operator and the toString() Method

Greetings to all in advance!

alert((~1).toString(2));

As a result, the output is: -10

However, in PHP/Java, it produces 11111111111111111111111111111110

I'm puzzled. What could be causing Javascript to include a "-" at the start of the output?

javascript operator-overloading bit-manipulation

Answer 1

Answer №1

It is common knowledge that Java utilizes two's complement to express negative numbers. The binary representation 11111111111111111111111111111110, achieved through ~1, signifies -2 or written as -10 with a negative sign.

To negate 10 (in base 2) using two's complement, the process involves inverting all the bits first:

11111111111111111111111111111101

Then adding 1 results in:

11111111111111111111111111111110

This concept seems to be applicable in Javascript as well.

Answer 2

It is common knowledge that Java utilizes two's complement to express negative numbers. The binary representation 11111111111111111111111111111110, achieved through ~1, signifies -2 or written as -10 with a negative sign.

To negate 10 (in base 2) using two's complement, the process involves inverting all the bits first:

11111111111111111111111111111101

Then adding 1 results in:

11111111111111111111111111111110

This concept seems to be applicable in Javascript as well.

Answer 3

Answer №2

One way to convert a number to an unsigned integer and then to binary is by using the shift operator >>>:

(~5 >>> 0).toString(2) // "11111111111111111111111111111010"

Answer 4

One way to convert a number to an unsigned integer and then to binary is by using the shift operator >>>:

(~5 >>> 0).toString(2) // "11111111111111111111111111111010"

Answer 5

Answer №3

Summary of Solution:

When applying a bitwise NOT operation (~1), the result is a 1's complement conversion of the decimal, which yields -2.
The .toString() function essentially converts the decimal without the sign (2) to binary (10), then adds a negative sign, resulting in -10.

Detailed Explanation:

The functionality lies within the method .toString(). When using .toString() on a number:

If the number is negative, the minus sign is preserved. This applies regardless of the base; the output is the positive binary representation preceded by a minus sign, not the two's complement.

According to developer.mozilla.org, there exists a formula for obtaining the 1's complement of an integer when performing a bitwise NOT (~) on a decimal:

Applying bitwise NOT to any number x results in -(x + 1). For example, ~5 equals -6.

This process can be better understood through a table and an illustration:

+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 10 Integer         | -3  | -2  | -1  | 0   | 1   | 2   | 3    |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 10 1's Complement  |  2  |  1  |  0  | -1  | -2  | -3  | -4   |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 2                  |     |     |     | 0   |  1  |  10 |  11  |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Result ~x.toString(2)   | 10  |  1  |  0  | -1  | -10 | -11 | -100 |
+-------------------------+-----+-----+-----+-----+-----+-----+------+

Commencing with the Base 10 integer "2"
The 1's Complement of Base 10 integer "2" corresponds to "-3", akin to executing a NOT (~)
The .toString function operates on the unsigned value (equal to "3" in base 10 and "11" in base 2)
The .toString function inserts a "-" symbol
The .toString output becomes "-11"

Answer 6

Summary of Solution:

When applying a bitwise NOT operation (~1), the result is a 1's complement conversion of the decimal, which yields -2.
The .toString() function essentially converts the decimal without the sign (2) to binary (10), then adds a negative sign, resulting in -10.

Detailed Explanation:

The functionality lies within the method .toString(). When using .toString() on a number:

If the number is negative, the minus sign is preserved. This applies regardless of the base; the output is the positive binary representation preceded by a minus sign, not the two's complement.

According to developer.mozilla.org, there exists a formula for obtaining the 1's complement of an integer when performing a bitwise NOT (~) on a decimal:

Applying bitwise NOT to any number x results in -(x + 1). For example, ~5 equals -6.

This process can be better understood through a table and an illustration:

+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 10 Integer         | -3  | -2  | -1  | 0   | 1   | 2   | 3    |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 10 1's Complement  |  2  |  1  |  0  | -1  | -2  | -3  | -4   |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Base 2                  |     |     |     | 0   |  1  |  10 |  11  |
+-------------------------+-----+-----+-----+-----+-----+-----+------+
| Result ~x.toString(2)   | 10  |  1  |  0  | -1  | -10 | -11 | -100 |
+-------------------------+-----+-----+-----+-----+-----+-----+------+

Commencing with the Base 10 integer "2"
The 1's Complement of Base 10 integer "2" corresponds to "-3", akin to executing a NOT (~)
The .toString function operates on the unsigned value (equal to "3" in base 10 and "11" in base 2)
The .toString function inserts a "-" symbol
The .toString output becomes "-11"

Answer 7

Answer №4

If you are operating in a 32-bit environment, the following code snippet is effective:

let value = parseInt("11110000", 2);
let complementResult = 0xFFFFFFFF - value;
console.log(complementResult.toString(2));

When executed, it yields the output: 11111111111111111111111100001111

Answer 8

If you are operating in a 32-bit environment, the following code snippet is effective:

let value = parseInt("11110000", 2);
let complementResult = 0xFFFFFFFF - value;
console.log(complementResult.toString(2));

When executed, it yields the output: 11111111111111111111111100001111

Answer 9

Answer №5

Check out this JavaScript solution for implementing the NOT operation. It may not be the most elegant, but it gets the job done.


// Using two's complement to implement a one's complement in JavaScript.
var num = 9;
num.toString(2);            //returns 1001
~(num - 1).toString(2);    //returns -1001
// Surprising results, right? The negative sign serves as a sign bit here.

If you need to see the binary string of a decimal after applying a NOT operation (bit toggle), use the code snippet below:

// Programmer: Larry Battle
// Objective: Create a bit toggle function in JavaScript.
var getStrCopy = function (str, copies) {
    var newStr = str;
    copies = (copies > 0) ? copies : 1;
    while (--copies) {
        newStr += str;
    }
    return newStr;
};
var convertDecToBase = function (dec, base, length, padding) {
    padding = padding || '0';
    var num = dec.toString(base);
    length = length || num.length;
    if (num.length !== length) {
        if (num.length > length) {
            throw new Error("convertDecToBase(): num(" + num + ") > length(" + length + ") too long.");
        }
        num = getStrCopy(padding, (length - num.length)) + num;
    }
    return num;
};
var formatBinaryStr = function(str){
    return str.replace(/\d{4}/g, '$& ').replace(/\s$/,'');
};
var toggleBits = function(dec, length, doFormat){
    length = length || 8;
    var str = convertDecToBase(dec, 2, length || 8);
    var binaryStr = str.replace(/0/g, 'o').replace(/1/g, '0').replace(/o/g, '1');
    return (doFormat) ? formatBinaryStr(binaryStr) : binaryStr;
};

// Make sure to run this in Firebug or Google Chrome Dev Tools
clear();
console.log(toggleBits(1));    // "11111110"
console.log(toggleBits(2));    // "11111101"
console.log(toggleBits(50, 16)); // "1111111111001101"
console.log(toggleBits(15, 8, true));    // "1111 0000"
console.log(toggleBits(520, 16, true)); // "1111 1101 1111 0111"

Answer 10

Check out this JavaScript solution for implementing the NOT operation. It may not be the most elegant, but it gets the job done.


// Using two's complement to implement a one's complement in JavaScript.
var num = 9;
num.toString(2);            //returns 1001
~(num - 1).toString(2);    //returns -1001
// Surprising results, right? The negative sign serves as a sign bit here.

If you need to see the binary string of a decimal after applying a NOT operation (bit toggle), use the code snippet below:

// Programmer: Larry Battle
// Objective: Create a bit toggle function in JavaScript.
var getStrCopy = function (str, copies) {
    var newStr = str;
    copies = (copies > 0) ? copies : 1;
    while (--copies) {
        newStr += str;
    }
    return newStr;
};
var convertDecToBase = function (dec, base, length, padding) {
    padding = padding || '0';
    var num = dec.toString(base);
    length = length || num.length;
    if (num.length !== length) {
        if (num.length > length) {
            throw new Error("convertDecToBase(): num(" + num + ") > length(" + length + ") too long.");
        }
        num = getStrCopy(padding, (length - num.length)) + num;
    }
    return num;
};
var formatBinaryStr = function(str){
    return str.replace(/\d{4}/g, '$& ').replace(/\s$/,'');
};
var toggleBits = function(dec, length, doFormat){
    length = length || 8;
    var str = convertDecToBase(dec, 2, length || 8);
    var binaryStr = str.replace(/0/g, 'o').replace(/1/g, '0').replace(/o/g, '1');
    return (doFormat) ? formatBinaryStr(binaryStr) : binaryStr;
};

// Make sure to run this in Firebug or Google Chrome Dev Tools
clear();
console.log(toggleBits(1));    // "11111110"
console.log(toggleBits(2));    // "11111101"
console.log(toggleBits(50, 16)); // "1111111111001101"
console.log(toggleBits(15, 8, true));    // "1111 0000"
console.log(toggleBits(520, 16, true)); // "1111 1101 1111 0111"

Exploring the JavaScript Bitwise NOT Operator and the toString() Method

Answer №1

Answer №2

Answer №3

Summary of Solution:

Detailed Explanation:

Answer №4

Answer №5

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