Using a random string generator in c++ constructor

» cpp » Using a random string generator in c++ constructor

By : L. Trong

Date : November 27 2020, 01:01 AM

help you fix your problem You call srand(time(NULL)) every time. That seeds the random number generator. If you call it within the same second, it has the same seed, and produces the same results.

code :

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How do I make my C# random number generator change with each time the constructor is called?

By : David Detlefsen

Date : March 29 2020, 07:55 AM

this will help If you initialize several Random instances using the default constructor, Random(), within a short time period, then you risk that they would end up with the same seed value (which is time-dependant) and, therefore, generate the same random sequence each time.
You can fix this issue by initializing a single static Random instance, and share it among all Student instances. This is perfectly safe as long as you’re not multi-threading.

code :

public class Student
{
    private static readonly Random random = new Random();        
}

public class Student
{
    private static Random random;

    private int[] numbers;

    public Student()
    {
        random = new Random();
        numbers = new int[10];
        for (int i = 0; i < 10; ++i)
            numbers[i] = random.Next();
    }
}

public class Student
{
    private static readonly Random random = new Random();

    private int[] numbers;

    public Student()
    {
        numbers = new int[10];
        for (int i = 0; i < 10; ++i)
            numbers[i] = random.Next();
    }
}

Guid.NewGuid() VS a random string generator from Random.Next()

By : Luana Manis

Date : March 29 2020, 07:55 AM

Any of those help
I am looking for a more in depth reason as to why the cooked up method may be more likely to generate collisions given the same degrees of freedom as a Guid.

How can I get java's random generator to produce a double for variable in a constructor statement?

By : user3293474

Date : March 29 2020, 07:55 AM

should help you out As Paul John said, Random.nextDouble() doesn't take any arguments. For what you're trying to do, you'd want code that would look like this:

code :

GPA = 3.5*generator.nextDouble()+0.5;

How to construct predefined random number generator and seed sequence in constructor?

By : MarijnvdZaag

Date : March 29 2020, 07:55 AM

wish help you to fix your issue Background , What I typically do is use a lambda.

code :

generator([]() -> auto& {
    static std::seed_seq seq(std::random_device()(), 
              duration_cast<nanoseconds>(system_clock::now().time_since_epoch()).count(),
              42);
    return seq;
}())

How to call the seed_seq constructor of a random generator from a member initialization list?

By : Panzer

Date : March 29 2020, 07:55 AM

wish helps you Just add std::seed_seq variable to the class before std::mt19937_64 (variables initialization order is important):

code :

class A
{
private:
    std::seed_seq seed_seq;
    std::mt19937_64 rng;

public:
    A(std::string const& seed)
        : seed_seq(seed.begin(), seed.end())
        , rng(seed_seq)
    {}

    std::uint32_t uniform()
    {
        return std::uniform_int_distribution<std::uint32_t>()(rng);
    }
};