[C++] DiceStats Program Help

[SirBernard]

/* Bernard Yeboah

January 03 2013

*/

```

#include

#include

#include

using namespace std;

int main(int argc, char *argv[])

{

//Declare Variables

int rolls[10];

int sim = 0, temp = 0;

cout.setf(ios::fixed);

cout.precision(4);

//Timer

time_t seconds;

time(&seconds);

srand((unsigned int)seconds);

//Initialize values for elements in the array

for (int i = 0; i < 11; i++)

rolls[i] = 0;

//Prompt user for the number of simulations

cout << "Enter the number of simulations: ";

cin >> sim;

//Display header(Table)

cout.setf(ios::left);

cout << setw(5) << "Value";

cout.unsetf(ios::left);

cout.setf(ios::right);

cout << setw(15) << "Frequency" << setw(15) << "Exp Prob" << setw(15) << "Theo Prob" << endl;

cout.unsetf(ios::right);

//Loop the simulation

for (int i = 1; i <= sim; i++)

{

temp = rand() % 6 + 1 + rand() % 6 + 1;

rolls[temp]++;

}

cout.setf(ios::right);

for (int i = 2; i < 13; i++)

cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;

system("PAUSE");

return EXIT_SUCCESS;

}

My goal is for it to display the frequency of the die rolls, and then also why doing this get the exponential and theoretical probabilities.[/i][/i][/i]
```

[SawQuart]

What do you want to fix exactly and what went wrong? I'd help you more but I dont have access to Visual Studio atm.

[SirBernard]

At the moment the displaying of the information is wrong and i don't see the solution. I get it to list all the dice roll possiblities for each.

Ex: if i run the program and choose to run it once. i get this

```

value frequency exp theo

2 1 1.000 0.0556

and so on...

```

it does that with correct frequencies and value until it gets to 12 then it start displaying random (Garbage, like the array that stores the 12th data is not being used…)

[Marsh]

```
int rolls[10];
```

```

//Initialize values for elements in the array

for (int i = 0; i < 11; i++)

rolls[i] = 0;

arrays start at 0 not one.

You are constantly going over the bounds of your array

[code]

for (int i = 2; i < 13; i++)

cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;

[/i][/i][/code][/i]
```

[SirBernard]

> ```
> int rolls[10];
> ```
>
> ```
>
> //Initialize values for elements in the array
>
> for (int i = 0; i < 11; i++)
>
> rolls[i] = 0;
>
> arrays start at 0 not one.
>
> what do you mean, i am lost. Do you mean the array it's self or do you mean the way i set it's values.[/i]
> ```

[Keebler Elf]

When you initalized your array you did "int rolls[10]" this gave you an array that had 11 slots because your array starts at zero meaning you have spaces "0 1 2 3 4 5 6 7 8 9 10". What Marshy Dearest is trying to show you is that when you did this

```

for (int i = 2; i < 13; i++) cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;

you have

int i = 2; i< 13;

So essentially you are trying to reference parts of the array that do not exist. It is looking for a rolls[11] rolls[12] and neither of those exist.[/i][/i]
```

[SirBernard]

> When you initalized your array you did "int rolls[10]" this gave you an array that had 11 slots because your array starts at zero meaning you have spaces "0 1 2 3 4 5 6 7 8 9 10". What Marshy Dearest Dearest is trying to show you is that when you did this
>
> ```
>
> for (int i = 2; i < 13; i++) cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;
>
> you have
>
> int i = 2; i< 13;
>
> So essentially you are trying to reference parts of the array that do not exist. It is looking for a rolls[11] rolls[12] and neither of those exist.
>
> oh thank you! wow i am stupid i didn't even notice i was doing that until you pointed it out.
>
> Thank you Marshy Dearest.[/i][/i]
> ```

[SirBernard]

i still get errors when i get to 11th and 12th row.

[Marsh]

> When you initalized your array you did "int rolls[10]" this gave you an array that had 11 slots because your array starts at zero meaning you have spaces "0 1 2 3 4 5 6 7 8 9 10". What Marshy Dearest is trying to show you is that when you did this
>
> ```
>
> for (int i = 2; i < 13; i++) cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;
>
> you have
>
> int i = 2; i< 13;
>
> So essentially you are trying to reference parts of the array that do not exist. It is looking for a rolls[11] rolls[12] and neither of those exist.
>
> Close
>
> You get 0 1 2 3 4 5 6 7 8 9
>
> 10 values. 0 to 9.
>
> Which is why you still get errors.
>
> So the first loop fails that i pointed out becouse it is reading 1 to high. The second one fails becouse you start at 2 not 0\. So you are trying to read 2 - 12\. nothing above 9 exists.[/i][/i]
> ```

[Marsh]

Here is the working code if you want it

```

#include

#include

#include

using namespace std;

int main(int argc, char *argv[])

{

//Declare Variables

int rolls[11];

int sim = 0, temp = 0;

cout.setf(ios::fixed);

cout.precision(4);

//Timer

time_t seconds = 0;

// time(&seconds);

srand((unsigned int)seconds);

//Initialize values for elements in the array

for (int i = 0; i < 10; i++)

rolls[i] = 0;

//Prompt user for the number of simulations

cout << "Enter the number of simulations: ";

cin >> sim;

//Display header(Table)

cout.setf(ios::left);

cout << setw(5) << "Value";

cout.unsetf(ios::left);

cout.setf(ios::right);

cout << setw(15) << "Frequency" << setw(15) << "Exp Prob" << setw(15) << "Theo Prob" << endl;

cout.unsetf(ios::right);

//Loop the simulation

for (int i = 1; i <= sim; i++)

{

temp = rand() % 6 + 1 + rand() % 6 + 1;

rolls[temp - 2]++;

}

cout.setf(ios::right);

for (int i = 2; i < 12; i++)

cout << setw(5) << i << setw(15) << rolls[i] << setw(15) << float(rolls[i]) / sim << setw(15) << i / 36.0 << endl;

system("PAUSE");

return EXIT_SUCCESS;

}

temp - 2 so you can fit the 12 into the 10 slot and the 2 will go into the zero spot. I also expanded your array to 11 instead of 10.[/i][/i][/i]
```

[SirBernard]

Thanks!

Just got a 50/50

[Marsh]

Nice!