What are namespaces, functors, and iterator classes in C++?
Namespaces reduced name collisions where an application may have various libraries of the same name. The using declaration makes it possible for a namespace without using a scope operator.
There are five types of iterator classes which input iterators, output iterators, forward iterators, and bidirectional iterators. These are usually stored in stored in lists and queues according to some ordering relation as defined in a binary tree.
Functors are a function pointer which holds the address of some pointer.
#include
using namespace std;
class Matcher
{
int target;
public:
Matcher(int m) : target(m) {}
int operator()(int x) { return x == target;}
};
int main() {
Matcher Is5(5);
int n=6;
if (Is5(n)) { // same as if (n == 5) return 0;
cout << "n and Is5 are equal" << endl;
}
else {
cout << "not equal"<
