ld returned 1 exit status error

ld returned 1 exit status error

I am writing a tester for a file HCTree.hpp that has a build() method but
when I try to run the tester I get "ld returned 1 exit status". What is
the problem? Here is the tester:
int main()
{
HCTree* pt;
vector<int> vec (256,0);
vec[0] = 1;
vec[1] = 3;
vec[2] = 2;
pt->build(vec);
return 0;
}