Your object "manager" is destroyed right after test() function is finished. To avoid this try to dynamically create object:
httpManager *manager;
void test()
{
manager = new httpManager();
manager->sendRequest("http://google.com/");
}
Notice that "httpManager *manager" is outside of any function.
Now your "manager" object is somewhere in memory (called heap) and not destroyed when test() function exits. Beware, this method not so good because "manager" now is global variable, that's not good way in Object Oriented Programming, but for the first time it doesn't matters.