c++ push back an array in a vector - c++

Question

i have an array of 9 numbers and my functions in my number class are used to reorder the 9 numbers in the array without any duplicate of numbers and then to list the number of times the rand() function was called.
I now need to generate ten lists of the numbers and store them into a vector.
here is the code:
class numbers{
private:
int indexCount;
public:
void swap (int *a, int *b)
{
int temp = *a;
*a = *b;
*b = temp;
}
void printArray (int arr[], int n)
{
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
cout << "random calls: " << indexCount <<endl;
}
void randomize (int arr[], int n)
{
indexCount=0;
srand (time(NULL));
for (int i = n - 1; i > 0; i--)
{
int j = rand() % (i + 1);
indexCount++;
swap(&arr[i], &arr[j]);
}
}
};
class numbersVector{
private:
vector <int>numberList;
public:
numbers num;
void storeInVector(int arr[], int n){
for (int i=0; i <10; i++){
num.randomize(arr,n);
num.printArray(arr,n);
numberList.push_back(arr[i]);
}
cout <<endl <<endl;
}
};
int main(){
numbers numbers;
numbersVector nv;
int arr[] = {1, 2, 3, 4, 5, 6, 0, 0, 0};
int n = sizeof(arr) / sizeof(arr[0]);
//numbers.randomize(arr, n);
// numbers.printArray(arr, n);
nv.storeInVector(arr,n);
return 0;
}
in my second class i loop over my functions in the first class to generate 10 list, i am now stuck on storing the randomised list into a vector.
My problem is, i can only store numbers from each list into the vector but i would like to store the 10 lists inside the vector.
EG
for (int i = 0; i <numberList.size(); i++)
{
cout <<numberList[i] <<endl;
}
i would want my output to be:
123456000 random calls: 8
02103654 random calls:8
and so on 10 times.
EDITING POST TO BE MORE CLEAR:
so i have an array
arr[] = {1,2,3,4,5,6,0,0,0}
after my randomise function i get a output like this
{2,1,0,0,6,0,4,3,5}
i then create a loop to run my randomise function 10 times.
ie
1)1,0,0,0,2,5,4,3,6
2)6,0,5,0,4,0,3,2,1
3)5,1,0,0,2,0,3,6,4
....
10)2,1,0,0,6,0,4,3,5
i would then like to store each generated list into a vector
IE
vector <int> numlist;
numList[1] = {1,0,0,0,2,5,4,3,6}
numList[2] = {6,0,5,0,4,0,3,2,1}
and so on

Answer 1

Lists aren't flattened in C++ as they are in some languages (notably perl). You need to specify where you want the elements in your new list inserted and which range you want to insert:
numberList.insert(numberList.end(), std::begin(new_list), std::end(new_list);
This would insert the full range of new_list at the end of your numberList.
Also: As #scohe001 mentioned, use <random> supported functions to get good randomization.
Example:
#include <random>
inline std::mt19937& generator() {
static thread_local std::mt19937 gen(std::random_device{}());
return gen;
}
//...
std::shuffle( numberList.begin(), numberList.end(), generator() );
Example after comments:
#include <algorithm>
#include <iostream>
#include <random>
#include <vector>
inline std::mt19937& generator() {
static thread_local std::mt19937 gen(std::random_device{}());
return gen;
}
int main() {
// a vector of vectors (not the most optimal but for this purpose, good enough)
std::vector<std::vector<int>> result;
std::vector<int> array{1, 2, 3, 4, 5, 6, 7, 8, 9};
for(int i = 0; i < 10; ++i) {
std::shuffle(array.begin(), array.end(), generator());
// pushing back an array (or better, a vector) into the vector
result.push_back(array);
}
//-- present the result
std::cout << result.size() << " random permutations (possibly duplicates):\n";
for(const auto& inner : result) {
for(int value : inner) {
std::cout << value << ' ';
}
std::cout << '\n';
}
}
Demo
If you can't use std::shuffle for some reason, you can make your own by adding a function to generate random numbers and then one to loop over the vector and swap random positions in it.
Example:
// generate a random number in the range [min, max]
template<typename T, std::enable_if_t<std::is_integral_v<T>>* = nullptr>
T my_rand(T min, T max) {
std::uniform_int_distribution<T> dist(min, max);
return dist(generator());
}
// a shuffle-like function
void shake_it(std::vector<int>& c) {
for(size_t i = 0; i < c.size(); ++i) {
std::swap(c[i], c[my_rand(0ul, c.size() - 1)]);
}
}
Then call it with shake_it(array); and it should be properly randomized.