How to detect double precision floating point overflow and underflow?

I have following variables:

double dblVar1;
double dblVar2;

They may have big values but less than double max.

I have various arithmetic on above variables like addition, multiplication and power:

double dblVar3 = dblVar1 * dblVar2; 
double dblVar4 = dblVar1 + dblVar2;
double dblVar5 = pow(dblVar1, 2);

In all above I have to check overflow and underflow. How can I achieve this in C++?