Specific bit inversion (JS implementation)

to Huawei interview, did not prepare for the job, the process of the interview did not ask clear also did not check, the results of a past let on the machine to do the problem, really a bit unprepared. The author is good at the front end of the Java Web Engineer Ah, basic knowledge of the underlying programming is already unfamiliar. Machine test questions encountered this bit operation of the topic, supposedly is very simple, the principle of the author is also very clear, but because it is really good for many years have not done bit operation, Java bit operation is no operation, so the result is not decent ...

Machine test time is one hours, language optional C or Java also has a scripting language, the author spent nearly three hours, only with Java reluctantly to make the problem, ashamed ashamed ... Back to the use of JS re-implemented a simple version, today to collate the paste out.

The title is: loop input each group of two number hex and N (0<=n<31), Hex is a 16 decimal number, we have to do is to reverse the nth position of hex, and then output the corresponding result in 16.

I toss two hours of the process will not repeat, here to give the implementation of JS, very simple bit operation of basic knowledge. The principle of a wordy, is to put 1 by the bit to the left of N-bit, and then the original number is different or on the line:

function Bitoper (hex, N) {    var num = parseint (hex);     Num ^= (1<<n);    return num.tostring (16);} Console.log (Bitoper (0x1234, 3));    123c

because the JS integer type has only a 32-bit limit, the above example code only supports the simple case of n<31 (the 31st bit is the sign bit).