Reverse array function - c++

Question

so I have made a program that works in the following way.
user decides how big the array is.
user then fills the array with x chosen integers, e.g. if they choose to make an array 5 large, they are then asked to fill the array with 5 numbers. However I'm a little stuck on how I can do this, once this bit is done everything else should work I believe as I have tested it by hard coding it with assigned values and the function dose reverse the program.
Here is my code.
#include <iostream>
using std::cout;
using std::endl;
using std::cin;
void reverse(int [], int);
void printarray(int [], int );
void printarray(int arr[], int count)
{
for(int i = 0; i < count; ++i)
cout<<arr[i]<<' ';
cout<<'\n';
}
void reverse(int arr[], int count)
{
int temp;
for (int i = 0; i < count/2; ++i)
{
temp = arr[i];
arr[i] = arr[count-i-1];
arr[count-i-1] = temp;
}
}
int main ()
{
int x;
cout << "how big is this thing " << endl;
cin >>
const int SIZE = x;
int arr [SIZE] = {., ., ., ., ., ., ., . , ., .};
cout<<"Before reverse\n";
printarray(arr, SIZE);
reverse(arr, SIZE);
cout<<"After reverse\n";
printarray(arr, SIZE);
return 0;
}
I do believe that I have to use a for loop or something to repeat and enter the integers into each index of the array, sorry it's been so long since I have done arrays.
Any help with this issue would be greatly appreciated.

Answer 1

You can try the following..
#include <iostream>
#include <string>
void reverse(int arr[], int count)
{
int temp;
for (int i = 0; i < count/2; ++i)
{
temp = arr[i];
arr[i] = arr[count-i-1];
arr[count-i-1] = temp;
}
}
void print_array(int my_array[], int array_size)
{
std::cout << "Your array: ";
for (int x = 0; x <array_size; x++) {
std::cout << my_array[x] << " ";
}
std::cout << std::endl;
}
int main()
{
int array_size;
std::cout << "how big is this thing " << std::endl;
std::cin >> array_size;
int my_array[array_size];
std::cout << "Please enter the elements of the array. Press ENTER after each element." << std::endl;
for (int x = 0; x <array_size; x++) {
std::cin >> my_array[x];
}
print_array(my_array, array_size);
std::cout << "Reverse array..." << std::endl;
reverse(my_array, array_size);
print_array(my_array, array_size);
}

Answer 2

This sounds like a homework exercise? In most cases you would be using something like std::vector but I guess for this you will need to be sticking to native arrays.
int arr[SIZE];
This will create an array on the stack, and the size must be known at compile time. If you don't know the size until runtime you will need allocate the array on the heap using the new keyword (or via something like malloc)
int *arr = new int[x];
You'll need to free this memory yourself once you're done though
delete[] arr;
That should be enough to get you started and point you int right direction. Hope that helps

Answer 3

Cause the size of array is unknown at compile time you can not use int array[SIZE] construct.
You need to allocate the memory at run-time with new:
int x;
cout << "how big is this thing " << endl;
cin >> x;
int *arr = new int[x];
for(int i = 0; i < x; i++) {
cout << "enter arry[" << i << "]" << endl;
cin >> arr[i];
}
cout<<"Before reverse\n";
printarray(arr, SIZE);
reverse(arr, SIZE);
cout<<"After reverse\n";
printarray(arr, SIZE);
delete[] arr;
The delete[] arr operator frees the allocated array. You should free every allocated memory blocks to avoid memory-leaks.

Answer 4

As mentioned from M.M, use std::vector and insert to the beginning of the vector (you don't need you're reverse)
#include <iostream>
#include <vector>
int main(int argc, char** argv)
{
std::vector<int> values;
int n_values;
std::cout << "How mutch numbers ?";
std::cin >> n_values;
std::cout << "Now Enter " << n_values << " Values : ";
for(auto i=0; i<n_values; i++)
{
int tmp;
std::cin >> tmp;
values.insert(values.begin(), tmp);
}
for(auto elem : values)
std::cout << elem << "\n";
return 0;
}