cout << oct << -12 << endl; ?

Code:

---

#include <iostream>
#include <iomanip>

using namespace std;

int main()
{
    int num;
    while (true)
    {
        cout << "N: ";
        cin >> num;
        if (! num) break;
        cout << hex << num << " " << dec << num << " " << oct << num << endl;
    }
   
    return 0;
}

---

output:
N: 12
c 12 14
N: -12
fffffff4 -12 37777777764
N:0

Question: Why negative numbers get strange values in hex and oct?
Actually I feel the hex value is natural, since that's how a negative number is internally. But why oct output is garbage?

Because hex and octal are defaulting to unsigned int instead of signed, it would appear.

--
Mats