Looking for a better randomization function.

CStoll

imho the rand() produces pretty good results, but maybe you shouldn't call srand() before every call (this needs to be called only once per application run to initialize the random number generator).

ice-man6969

I wanted to make some experiments on the "Martingale System" of gambling.
"KEEP ON DOUBLING" system as explained at this link:
http://www.smartgambler.com.au/guide/myths.html

I think you're all wrong people.
Try inserting 80000 several times and look at the final results. You will ultimately get the same "max_lost" (=15) and "num_max_lost" (=3267 one more or one less).
If it was random you would get different results after a while at least. Bigger standard deviation than one that's for sure!

How would you all explain that?

This is my program. Just copy, past and execute:

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

#define FIRST_BET 2

void main()
{
	int bank=0, bet=FIRST_BET, wins=0, max_lost=0, num_max_lost=0, losts=0;
	bool bol=false;

	puts("What is your initial bank?");
	scanf("%d", &bank);

	srand( (unsigned)time( NULL ) );

	while (bank>0 && bank<12345678912)
	{

		if (rand()%2)
		{
			//WON
			bol = true;

			wins++;
			bank += bet;
			bet = FIRST_BET;
			losts=0;

		}
		else
		{
			//LOST
			bol = false;

			losts++;
			bank-= bet;

			if (losts>max_lost)
			{
				max_lost = losts;
				num_max_lost=1;			}
			else if (losts==max_lost)
			{
				num_max_lost++;
			}

			bet *= 2;
		}
	}

	printf("\nRESULTS\n");

	printf("\nbank = %d\nwins = %d\nmax_lost = %d\nnum_max_lost = %d\nlosts = %d\n\n",
			bank, wins, max_lost, num_max_lost, losts);

	if (bol)
		printf("WIN");
	else
		printf("LOST");

}

isabeau

All your base are belong to us.
http://www.c-plusplus.net/forum/viewtopic-var-t-is-118802-and-highlight-is-*random*.html

[edit] same:
http://www.c-plusplus.net/forum/viewtopic-var-t-is-118802.html
[/edit]

ice-man6969

isabeau, I didn't succeed on integrating the code given there with my project and I don't speak that language... :-\

Can you or anyone alse integrate it and post the complete code?

Thanks.

MFK

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

#define FIRST_BET 2

class Random{
private:
    unsigned __int64 x;
public:
    Random(unsigned __int64 seed){
        x=seed|(unsigned __int64(1)<<32);
    }
    unsigned int operator()(){
        x=1967773755*(x&0xffffffff)+(x>>32);
        return x;
    }
}; 

void main()
{
    Random r(time(0));

    int bank=0, bet=FIRST_BET, wins=0, max_lost=0, num_max_lost=0, losts=0;
    bool bol=false;

    puts("What is your initial bank?");
    scanf("%d", &bank);

    while (bank>0 && bank<12345678912)
    {

        if (r()%2)
        {
            //WON
            bol = true;

            wins++;
            bank += bet;
            bet = FIRST_BET;
            losts=0;

        }
        else
        {
            //LOST
            bol = false;

            losts++;
            bank-= bet;

            if (losts>max_lost)
            {
                max_lost = losts;
                num_max_lost=1;            }
            else if (losts==max_lost)
            {
                num_max_lost++;
            }

            bet *= 2;
        }
    }

    printf("\nRESULTS\n");

    printf("\nbank = %d\nwins = %d\nmax_lost = %d\nnum_max_lost = %d\nlosts = %d\n\n",
            bank, wins, max_lost, num_max_lost, losts);

    if (bol)
        printf("WIN");
    else
        printf("LOST");

}

ice-man6969

Thanks a lot people !
Now that program actually shows that the "doubling" system will leave you broke
This function gives much better results in my humble opinion...

Just two more small questions.

How can I ask for numbers between 0-5 for example?
How can I print an unsigned-long-type-variable ?
I've tried using printf("ul", ulvar); and printf("l", ulvar); and printf("l", ulvar); but none printed the var 123456789123 as it is.

Lots and lots of thanks 2 all of you!!!

ice-man6969 schrieb:

How can I ask for numbers between 0-5 for example?

just use "r()%6" as your calculation number (in general, to generate numbers between minv and maxv, you need "rand()%(maxv-minv+1)+minv")

How can I print an unsigned-long-type-variable ?

printf("%lu",val);

(%u displays an int as unsigned value, the l modifier denotes to use long instead of int)

ice-man6969

I g2g now so i'll try to use the functions later and let you know how I did

Thanks a lot !

ice-man6969

Something is messed up...
I've tried using this code:

unsigned long l;

	puts("enter a number:");
	scanf("%lu", &l);

	printf("\n\n %lu \n\n", l);

But is prints some other number instead of 12345678912 and all the numbers above this one...

How come?

MFK

Is your unsigned long a 64 bit type? Otherwise, 12345678912 won't fit.

ice-man6969

I don't know but I succeeded doing scan and print with an int with the number 1234567891 so I thought that unsigned long could contain more digits...

I don't seem to make it work. I've tried all kind of things but nothing was successful. :-\

MFK

ice-man6969 schrieb:

so I thought that unsigned long could contain more digits...

The standard says that long is at least as big as int, but it doesn't have to be larger.

What do you get for sizeof(unsigned long)?

The maximum value you can store in an unsigned 32 bit value is 2^32 - 1 = 4,294,967,295.

ice-man6969

sizeof(unsigned long) = 4
but also
sizeof(unsigned int) = 4

so what is the use of long ?????? :-\

MFK

ice-man6969 schrieb:

so what is the use of long ?????? :-\

The standard requires this type. That's all there is to it.

You can use unsigned __int64. The format specifier for printf and scanf is %I64u. Note that this is Microsoft-specific.

ice-man6969

Thanks MFK !!!

And again thanks to everyone !!!