The C++ course FAQ

I daresay you did not really look well enough. I just ran "c++ iterator" on Google and found many interesting results.

In any case, an iterator is the STL-equivalent to a pointer used to "travel along" an array. If you use a "pure C" array like

 char array[10] = "wow";

 for(char* ptr = array; *ptr != '\0'; ptr++) {
   cout << *ptr;
 }

 vector myVector;
 // fill the vector
 for(vector::iterator vi = myVector.begin(); vi != myVector.end(); vi++){
   cout << *vi;
 }

More precisely, iterators are objects for which the unary operator * and the increment and decrement operators ++ and -- have been overloaded, so that they behave like pointers. An iterator does NOT contain, like a pointer does, simply a memory address. But an iterator will contain some private data which allows it to behave like a pointer (i.e. one of its fields contains a memory address). The overloaded unary operator * will return the object pointed to by the private data contained within the iterator, and the overloaded ++ (respectively --) operator will change the private data within the iterator so that the iterator "points" to the next (respectively previous) element in the STL container.

One important caveat: whereas pointers obey a linear ordering, iterators do not necessarily do so. In other words, if two pointers

  char* p1;
  char* p2;

  p1++;

  p1 == p2

 for(vector::iterator vi = myVector.begin(); vi < myVector.end(); vi++){
   cout << *vi;
 }

 string myString = "wow";
 char* myArray = myString.c_str();