Question

In C++11 if we try to allocate array with negative size using global operator new, it will throw std::bad_array_new_length, but what about C++98 / C++03? Is it UB or will throw std::bad_alloc?

int main()
{
   int* ptr = new int[-1];
}

Answer 1

The program is incorrect if the size is negative 5.3.4p6 from the C++03 standard:

Every constant-expression in a direct-new-declarator shall be an integral constant expression (5.19) and evaluate to a strictly positive value. The expression in a direct-new-declarator shall have integral or enumeration type (3.9.1) with a non-negative value.

The above quote covers new T[a][b];, where b is the constant-expression according to the grammar and a is the expression (only the first dimension).