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javascriptbitbitwise-not

JavaScript bitwise NOT ~ doesn't produce same result

I am attempting to invert the binary digits of a base-10 value using JavaScript, according to this W3Schools page, JavaScript's Bitwise NOT operator (i.e. ~) should do just that.

In an example they show ~5 resulting in a value of 10, but when I attempt to execute the simple program ...

console.log(~5);

... the RTE logs -6, not 10. What am I doing wrong?

Solution

  • If you scroll down a bit at the website (https://www.w3schools.com), you find this information (as axiac has already written):

    The examples above uses 4 bits unsigned binary numbers. Because of this ~ 5 returns 10.

    Since JavaScript uses 32 bits signed integers, it will not return 10. It will return -6.

    00000000000000000000000000000101 (5)

    11111111111111111111111111111010 (~5 = -6)

    A signed integer uses the leftmost bit as the minus sign.

    So you didn’t do anything wrong.


    var x = 5;
document.getElementById("output").innerHTML=~5;
    <div id="output"></div>