generate random numbers and put them in an array - c++

Question

I'm looking to write a little dice game called Farkle (you may know it from Kingdom come delivarance) in C++ but I'm still learning, so I have some trouble with it.
atm I'm trying to roll 6 dice and put every rolled number in an array to be able to work with it afterwards. everything seem to work fine but Visual Studio ist outputting this error Code:
Run-Time Check Failure #2 - Stack around the variable 'die' was corrupted.
this is my code:
#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
void dice() {
int die[5];
int i = 1;
while (i <= 6) {
die[i] = rand() % 6 + 1;
cout << die[i];
i++;
}
}
int main()
{
srand(time(NULL));
dice();
system("STOP");
return 0;
}
is ths actually the right approach for this kind of programm?

Answer 1

No, a better way to generate uniformly distributed random numbers would be
#include <random>
#include <algorithm>
std::random_device rd; //Will be used to obtain a seed for the random number engine
std::mt19937 gen(rd()); //Standard mersenne_twister_engine seeded with rd()
std::uniform_int_distribution<> d6(1, 6); // {1, 2, 3, 4, 5, 6} with equal probability
int die[5];
std::generate(die, die + 5, [&gen, &d6](){ return d6(gen); });
If you were generating multiple sets of 5d6, you can re-use the same gen rather than re-initialising it each time

Answer 2

As others pointed out. Your error stems from using a too small array. This post will be more about your code being more like C.
It is more idiomatic in C++ to use std::array instead of raw arrays.
Also it is recommended not to use rand() since it produces bad random numbers and by using the modulo operation you are introducing additional bias to you random numbers. Instead one should use the classes from the <random> header.
To make the code even more readable you could try to use the functions from the <algorithm> to replace you loops by named algorithms.
This leads to following code:
#include <algorithm>
#include <array>
#include <iostream>
#include <iterator>
#include <random>
void dice() {
std::array<int, 6> die;
std::mt19937 gen{std::random_device{}()};
std::uniform_int_distribution<int> dice_roll{1, 6};
std::generate(begin(die), end(die), [&] { return dice_roll(gen); });
std::copy(begin(die), end(die), std::ostream_iterator<int>{std::cout});
}
int main() {
dice();
std::cin.get();
}

Answer 3

You have 2 problems in your code:
The size of your array is 5, but you access 6 indices (1 to 6), you can avoid this by changing the <= to < in the condition.
The indices of an array in C++ start with 0, but you start with 1. You can fix that if you change each die[i] to die[i-1] in your code.
Another approach (fixing both problems) would be to initialize i=0 and go with while (i < 5)

Answer 4

index i should be from 0 to 5, not 1 to 6.
It's obvious that when i = 6, it run out of the range of dice which made an error.
Edit these lines:
int i = 0;
while (i <= 5) {
....

Answer 5

Try this code :
#include <iostream>
#include <cstdlib>
#include <ctime>
void populateArray( int ar[], /*const*/ int n )
{
for( int i = 0 ; i < n ; ++i ) ar[i] = std::rand() % 50 + 1 ;
}
int main()
{
// http://en.cppreference.com/w/cpp/numeric/random/srand
std::srand( std::time(nullptr) ) ; // **** important ****
const int ARRAY_SIZE = 50;
int ar[ARRAY_SIZE] = {0} ;
populateArray( ar, ARRAY_SIZE ) ;
for( int v : ar ) std::cout << v << ' ' ;
}