coin toss using a class

[Bking419]

Im having trouble with the random generator. It only displays "heads" first.
I'm also having trouble with the counting how many times each side has been displayed, I know im going to use a for loop but I cant think of how to format it.

  #include<iostream>
#include<ctime>
#include<time.h>
#include<stdlib.h>
using namespace std;


class coin
{
private:
	int Sideup;
	int heads = 1;
	int tails = 0;

public:
	void flip()
	{
		int srand = (time(NULL)) ;
		int NUM =srand;
		if (NUM = 1, rand()%2)
		{
			
			cout << "heads\n";
		}
		else
		{
			cout << "tails\n";
		}

	}

	int getSideup()
	{
		Sideup++;
		return Sideup;
	}


};

int main()
{
	coin c;
	int n=0;
	//while (n != 20)
	//{
		c.flip();
		c.flip();
		c.flip();
		c.flip();

	//}
	/*cout << "Tails was tossed " << tails << " Sideup" << endl;
	cout << "Heads was tossed " << heads << " Sideup" << endl;*/


	system("pause");
	return 0;
}

[RUNNER PRO AGARIO]

On a sidenote, not answering your question: just to be cross-platform friendly, use std::cin.get(); instead of system("pause");

[Bking419]

I just comment that out to do some debugging. I thought "using namespace std" took care of me having to use std

[RUNNER PRO AGARIO]

Oh, wait I didn't see that statement. It is good to not get into the habit of writing using namespace std;

rather you should do what I do, or write the std:: prefix

using std::cout;
using std::cin;
using std::endl;
using std::string;
and so on...

[Bking419]

oh ok, well do you have any insight as to why i keep getting the same output lol I'm a little lost

[RUNNER PRO AGARIO]

Wait, what I don't get is why you have "rand() % 2" at line 20's if statement. Also, why not just create srand equal to rand()%2 in the first place?

[Bking419]

yea I changed that when I realized what I did

#include<iostream>
#include<ctime>
using namespace std;


class coin
{
private:
	int Sideup;
	int heads = 0;
	int tails = 0;

public:
	void flip()
	{
		srand(time(NULL));
		int NUM = rand()%2;
		if (NUM = 1)
		{
			
			cout << "heads\n";
		}
		else
		{
			cout << "tails\n";
		}
		

	}

	int getSideup()
	{
		
		Sideup++;
		return Sideup;
	}


};

int main()
{

	coin c;

	c.flip();
	
		
	/*cout << "Tails was tossed " << tails << " Sideup" << endl;
	cout << "Heads was tossed " << heads << " Sideup" << endl;*/


	system("pause");
	return 0;
}  

[RUNNER PRO AGARIO]

Lol, as long as it worked.

[JLBorges]

#include <iostream>
#include <ctime>
#include <cstdlib>

class coin
{
    private:
        int heads = 0;
        int tails = 0;

    public:
        void flip()
        {
            if( std::rand() % 10000 < 5000 ) // we don't want to rely on the last bit being random
            {
                std::cout << "heads\n";
                ++heads ;
            }
            else
            {
                std::cout << "tails\n";
                ++tails ;
            }

        }

        int num_heads() const { return heads ; }
        int num_tails() const { return tails ; }
        int num_flips() const { return num_heads() + num_tails() ; }
};

int main()
{
    std::srand( std::time(nullptr) ) ; // seed once, at the very beginning

    coin c ;

    const int nflips = 20 ;
    for( int n = 0 ; n < nflips ; ++n ) c.flip() ;

    std::cout << "\ntotals - heads: " << c.num_heads() << "  tails: " << c.num_tails() << '\n' ;

    std::cout << "\npress enter to quit" ;
    std::cin.get() ;
}

[Bking419]

thank you for your help, what was I doing wrong

[JLBorges]

> what was I doing wrong

Re-seeding the rng each time flip is called.
Not keeping track of the number of heads and tails.
Failing to initialise the member variable Sideup.
Relying on the randomness of a particular bit in numbers generated by a poor rng.

[Bking419]

OK thank you so seeding in done in main to assure its only done once? also what makes a poor rng? I'm asking because the only examples I found were using the modulus 2 form.

[JLBorges]

> seeding in done in main to assure its only done once?

Yes.
Also, components other than main() shouldn't make program-wide policy decisions (like how a shared rng is seeded).


> also what makes a poor rng?

There are no guarantees as to the quality of the random sequence produced. In the past, some implementations of rand() have had serious shortcomings in the randomness, distribution and period of the sequence produced (in one well-known example, the low-order bit simply alternated between 1 and 0 between calls).
rand() is not recommended for serious random-number generation needs, like cryptography. It is recommended to use C++11's random number generation facilities to replace rand().
http://en.cppreference.com/w/cpp/numeric/random/rand

A numeric sequence is said to be statistically random when it contains no recognizable patterns or regularities
https://en.wikipedia.org/wiki/Statistical_randomness

[Bking419]

ok thanks I guess this is the stuff they don't teach you in school lol I appreciate it