The following code produces an error that says that it should be reported :

#include<ginac/ginac.h>
#include<iostream>

int main(int argc, char* argv[])
{
  GiNaC::symtab table;
  table["x"] = 2.34;
  GiNaC::parser p(table);
  GiNaC::ex e = p("2*cos(x)+e^x");
  GiNaC::numeric n = GiNaC::ex_to<GiNaC::numeric>(e);
  double x = GiNaC::ex_to<GiNaC::numeric>(n.evalf()).to_double();
  std::cout << x << std::endl;
  return 0;
}