Error ?

Question

int a = 07; // Error?

Answer 1

...
int main()
{
int a = 07;
cout << a;
}

Octal or zero ? How distinguish ?

Answer 2

Task from Challenge. I not understand too, why error.

Answer 3

Perhaps, but not happened so far...although I played enough.

Answer 4

Yes, I know. Thank, Ipang. Dont.

Answer 5

Dont comment.