Dice roll generator

[Metalman]

Hello all

So what am trying to do is write a program that will simulate the rolling of a single dice using rand() and time.h.

1)The user will input the number of times he wants the dice to be rolled.
2)The generator will roll the dice X times and count the times each one of 1-6 number was generated and save them in an array.
3)It well then count the percentage each of the 6 numbers was generated and save it in another array.
4)It will then find the minimum and maximum percentage and subtract max-min and if its more than 5% it will print a message that says the generator is faulty.

I need to make a histogram for each number with +,- axis and stars but I really haven't gotten there yet cause it definitely sounds scary.

So I hope I made everything clear.
This is my code which gives awkward results.
P.S It compiles ok but the results are strange.

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

int random_number();
float calc_percentage(int totals, int nums);
float calc_maxper(float perc[6]);
float calc_minper(float perc[6]);
float permin;
float permax;


int main(void)
{
    int nums;
    int i;
    int totals[6] = {0};
    float percentages[6] = {0};
    
    srand(time(NULL));
    
    printf("How many numbers to generate?");
    scanf("d%", &nums);
    
for (i = 1; i <= nums; i++)
	{
	    int x = random_number();
	    totals[x-1]++;   
       printf("%d", x);
	}
	
for (i = 0; i<6; i++)
{
    percentages[i] = calc_percentage(totals[i],nums);
    printf("The percentage of each number is: %.2f%\n", percentages[i]);
}


permin = calc_minper(percentages);
permax = calc_maxper(percentages);

if (((permax) - (permin)) > 5)
   printf("According to the percentages of each number the generator is diss-functional\n");
   printf("%.2f\n", permin);
   printf("%.2f\n", permax);
   
system("pause");
return 0;
}



int random_number()
{
    int randnum;
    randnum = 1 + (rand() % 6);
    
    return randnum;
}

float calc_percentage(int totals, int numbers)
{
      float a;
      
      a = (totals * 100)/numbers;
      
      return a;
}

float calc_minper(float perc[6])
{
       int i;
       float min;
       min = perc[0];
       
       for (i=1; i<6; i++)
           {
                 if (perc[i] < min)
                    min = perc[i];
           }
       return min;
}

float calc_maxper(float perc[6])
{
       int i;
       float max;
       max = perc[0];
       
       for (i=1; i<6; i++)
           {
                 if (perc[i] > max)
                    max = perc[i];
           }
       return max;
}

Hope I get some ideas from all you.
-Thanks in advance!!

[johny10151981]

your scanf function is not returnning anything. cause its wrong :)

scanf("d%", &nums); //wrong
//it would be 
scanf("%d", &nums);

[Metalman]

Damn lol thanks man!!!

It works ok now but it doesnt give full 100% if i add the percentage of all numbers. It goes up to like 95%-98%. Why is this happening?

Also, any idea on how to make an histogram like this for my case?

10%|*
8% |* * *
6% |* * * * *
4% |* * * * * *
2% |* * * * * *
+------------
1 2 3 4 5 6

[donbock]

calc_percentage () truncates the fractional percentage. That is, each of the six percentages is underestimated by error E where 0 <= E < 1. The sum all all six percentages thus ends up with error 6E, where 0 <= 6E < 6.

[Metalman]

You are right man. Thanks a lot. Do you know what could possibly cause this? I mean it shouldnt do that since the variables are all float.

[donbock]

The percentage variables are all float but the equation is all integer. Thus, the computation uses integer math to get an integer result which is then stored in a floating point variable.

You can force the computation to use floating point math by insuring that at least one term is floating point. Change "100" to "100.".

[Metalman]

Yes man thank u for correcting me but thats the old code
It isnt corrected or updated.
Here is the (almost) final one:

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

int random_number();
float calc_percentage(int totals, int nums);
float calc_maxper(float perc[6]);
float calc_minper(float perc[6]);


int main(void)
{
    int nums;
    int i;
    int totals[6] = {0};
    float percentages[6] = {0};
    float permin;
    float permax;

    srand(time(NULL));
    
    printf("How many numbers to generate?");
    scanf("%d", &nums);
    
for (i = 1; i <= nums; i++)
	{
	    int x = random_number();
	    totals[x-1]++;
	}
	
for (i = 0; i<6; i++)
{
    percentages[i] = calc_percentage(totals[i],nums);
}


permin = calc_minper(percentages);
permax = calc_maxper(percentages);

if (((permax) - (permin)) > 5)
   printf("The generator is not reliable.\n");
   printf("The percentage difference is:%.1f\n\n", permax-permin);
   
   
    printf("20%|");
    for (i=0; i<6; i++)
    {
        if (percentages[i] >= 20)
           printf("* ");
    }
    printf("\n");
    
    printf("16%|");
    for (i=0; i<6; i++)
    {
        if (percentages[i] >= 16)
           printf("* ");
    }  
    printf("\n");
   
    
    printf("12%|");
    for (i=0; i<6; i++)
    {
        if (percentages[i] >= 12)
           printf("* ");
    }  
    printf("\n");
    
    
    printf(" 8%|");
    for (i=0; i<6; i++)
    {
        if (percentages[i] >= 8)
           printf("* ");
    }  
    printf("\n");
    
    
    printf(" 4%|");
    for (i=0; i<6; i++)
    {
        if (percentages[i] >= 4)
           printf("* ");
    }  
 
       

printf("\n");
printf("  +------------\n");   
printf("   1 2 3 4 5 6\n");
   
   
   
   
system("pause");
return 0;
}



int random_number()
{
    int randnum;
    randnum = 1 + (rand() % 6);
    
    return randnum;
}

float calc_percentage(int totals, int numbers)
{
      float a;
      
      a = (totals * 100)/numbers;
      
      return a;
}

float calc_minper(float perc[6])
{
       int i;
       float min;
       min = perc[0];
       
       for (i=1; i<6; i++)
           {
                 if (perc[i] < min)
                    min = perc[i];
           }
       return min;
}

float calc_maxper(float perc[6])
{
       int i;
       float max;
       max = perc[0];
       
       for (i=1; i<6; i++)
           {
                 if (perc[i] > max)
                    max = perc[i];
           }
       return max;
}

[donbock]

The corrected and updated code still contains the same mistake in calc_percentage that I described in my previous post.