In the past, the only standard we had for random number generation was rand() and srand() in the c library, but with the introduction of the c++11 standard, we now have a newer and much better way for random number generation: the <random> header! Yay! I know so exciting. I’m going to show some of the ways you can make random numbers.

Step 1: Initializating a generator object,

This is easy. You have several different PRNG(pseudorandom number generator) classes to choose from, but for this tutorial I will be using the mt19937 generator class. When declaring a PRNG object like mt19937, the generator is seeded with a special number that it uses to kinda 'kick off' it’s generation. Kinda like with srand(), most people will use the time to initialize the object.

#include <chrono>
#include <random>
int main () {
unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
std::mt19937 rnd (seed);
}

In my opinion, this is the most ridiculous and excessive initialization I’ve ever seen in my life. I’m just going to use 0.

#include <random>
int main() {
std::mt19937 gen(0);
}

Step 2: use it.

Woah! The tutorial’s already done?!?

yes.

int random_number = gen();

Edit: Aw man wait I missed the best part of the new <random> header: unbiased distribution!

For this you just make a distribution object. You can either make one for real numbers (like -1.84 or 6.6) or integers (like 1 or -3) To do this you just initialize the object with the range that the number should be in between, along with the type of the random numbers as a template argument like so..

#include <random>
int main() {
std::uniform_int_distribution dist<int> (1,100);
}

And then to use the distribution, you just pass the generator that you declared before:

int random_number = dist(gen); // make a random number from 1 to 100

In the past, the only standard we had for random number generation was rand() and srand() in the c library, but with the introduction of the c++11 standard, we now have a newer and much better way for random number generation: the <random> header! Yay! I know so exciting.

So you say that this new method of generating random numbers is much better. Just a question, how is it better than rand() or srand() (just curious, I don't even know C/C++)

@MatthewDoan1 I have heard time and again that rand is pretty bad, and also you would have to figure out yourself how to make a random number within a range which isn’t biased, for example modding a random number will generally not produce an unbiased result because our random numbers aren’t arbitrarily large, they are already produced within a range which makes it more likely you get certain numbers in that range. Also the periodicity of the generators is much bigger.

@MatthewDoan1 🤷♂️ Features of c++ are put in the standard library according to importance and you could make your own random number generator pretty easily and make unbiased ranged results pretty easily. For example I know an algorithm for making random numbers and I don’t know why I know it: it super easy to find a solution.

In the past, the only standard we had for random number generation was

`rand()`

and`srand()`

in the c library, but with the introduction of the c++11 standard, we now have a newer and much better way for random number generation: the <random> header! Yay! I know so exciting.I’m going to show some of the ways you can make random numbers.

## Step 1: Initializating a generator object,

This is easy. You have several different PRNG(pseudorandom number generator) classes to choose from, but for this tutorial I will be using the mt19937 generator class.

When declaring a PRNG object like mt19937, the generator is seeded with a special number that it uses to kinda 'kick off' it’s generation. Kinda like with srand(), most people will use the time to initialize the object.

In my opinion, this is the most ridiculous and excessive initialization I’ve ever seen in my life.

I’m just going to use 0.

## Step 2: use it.

Woah! The tutorial’s already done?!?

yes.

Edit:

Aw man wait I missed the best part of the new <random> header: unbiased distribution!

For this you just make a distribution object. You can either make one for real numbers (like -1.84 or 6.6) or integers (like 1 or -3)

To do this you just initialize the object with the range that the number should be in between, along with the type of the random numbers as a template argument like so..

And then to use the distribution, you just pass the generator that you declared before:

So you say that this new method of generating random numbers is much better. Just a question, how is it better than

`rand()`

or`srand()`

(just curious, I don't even know C/C++)@MatthewDoan1 I have heard time and again that rand is pretty bad, and also you would have to figure out yourself how to make a random number within a range which isn’t biased, for example modding a random number will generally not produce an unbiased result because our random numbers aren’t arbitrarily large, they are already produced within a range which makes it more likely you get certain numbers in that range. Also the periodicity of the generators is much bigger.

@Highwayman Wow, so it took that long for C++ to have an actually decent random algorithm?

@MatthewDoan1 I will say this though: it’s a lot easier to make a random number with just srand(), rand(), and a modulous operation.

@MatthewDoan1 🤷♂️ Features of c++ are put in the

standardlibrary according toimportanceand you could make your own random number generator pretty easily and make unbiased ranged results pretty easily. For example I know an algorithm for making random numbers and I don’t know why I know it: it super easy to find a solution.