Iterate through a C++ Vector using a 'for'

Question

I am new to the C++ language. I have been starting to use vectors, and have noticed that in all of the code I see to iterate though a vector via indices, the first parameter of the for loop is always something based on the vector. In Java I might do something like this with an ArrayList:

for(int i=0; i < vector.size(); i++){
   vector[i].doSomething();
}

Is there a reason I don't see this in C++? Is it bad practice?

Answer 1

The right way to do that is:

for(std::vector<T>::iterator it = v.begin(); it != v.end(); ++it) {
    it->doSomething();
 }

Where T is the type of the class inside the vector. For example if the class was CActivity, just write CActivity instead of T.

This type of method will work on every STL (Not only vectors, which is a bit better).

If you still want to use indexes, the way is:

for(std::vector<T>::size_type i = 0; i != v.size(); i++) {
    v[i].doSomething();
}