Int, not an unsigned int of an array length

I would like to share impressions with variable length array member of a class that is recorded to a tree. I cant draw this array in root cint. I searched for mistake for a long time. It was found that length of array member must be integer, not an unsigned integer!

All the best,

As usually. Details? Small code sample?
There are no variable size arrays in C++, but there can be dynamically allocated objects.

In your class do something like

int n; double* myarray; //[n]
see doc about I/O. the [n] must be an int, not an unsigned int