Trying to make a function that finds the Fibonacci number of a user input number

I am trying to make a program where the user enters a number, then that number is entered into a function and it outputs the element of the Fibonacci sequence that that number is.

It's giving me an error that says

stack around the variable 'fib' was corrupted

I don't know if this is a logic error or a program error. Also I don't know if my logic for finding the Fibonacci number is correct.

#include <iostream>
using namespace std;

int Fibonacci(int num)
{
    int fib[] = { 0 }, answer, i = 3;
    fib[1] = fib[2] = 1;
    fib[0] = 0;
    for (i = 3; i < num; i++)
    {
        fib[i] = fib[i - 2] + fib[i - 1];
    }

    answer = fib[num];
    return answer;
}

int main()
{
    int user_number, i = 0;
    cin >> user_number;
    cout << Fibonacci(user_number) << endl;

    return 0;
}