Random integer in the range without random library-CodePudding

I have a question about randomizing a number from a range without using the random library and similar.

I have seen the use of a method to generate noise from a microphone, but it does not have a given range.

Is there anything else? Because I couldn't find any more example of using it with user input (like CPU temp or current date).

CodePudding user response：

Well, this isn't truly random as I mentioned in the comments. But it does what you ask.

So the range is from min to max-1 inclusive.

public static long rand(int min, int max) {
    return (System.nanoTime()%(max-min))   min;
}

CodePudding user response：

You can generate a psudo-random number using a seed based on:

For generating psudo-random numbers nowadays it is most commonly used LFSR (Linear Feedback Shift Register) based on logic operations.

The process would be something like this:

Start with a binary seed like for instance with 5 bits you can generate up to 2^5 -1 random numbers.

Lets put an example. Starting with 01101:

Extract last bit from the seed
Move forward the other bits and do XOR of last 2 bits In this case XOR of 0 & 1 is = 1 the result would be 10110
Repeat this process to generate new numbers this is close to throwing a coin to the air almos random.