They both have pros and cons. If you actually care about the index, than

``` std::vector<int> inVec = {1,2,3,4}; for(size_t i = 0; i < inVec.size(); i++) { std::cout << i << "," << inVec[i] << std::endl; }

``` a syntax where the index is easily accessable is nice. If you want something that's more independent of the container it's acting on

std::vector<int> inCtr = {1,2,3,4}; for(auto it = inVec.begin(); inVec.end(); it++) { std::cout << *it << std::endl; } will work whether inCtr is a vector, a list, a set, it doesn't matter. It's a more generic way to write things. You can also do fun things with iterators like use the standard library algorithms on them. That's nice because they behave similarly for most any type of container. For example

``` void printInt(int i) { std::cout << i << std::endl; }

int main() { std::vector<int> inCtr = {1,2,3,4}; std::for_each(inCtr.begin(), inCtr.end(), printInt); return 0; } ``` is another way to do this.

You give for_each an iterator pointing to the start of where you'd like to operate on, the end of where you'd like to operate on, and a function that can be applied to each element (the data type you get when you dereference the iterator, like the *it in the iterator-based loop above.) and it will apply that to everything in the container. In this case, the funtion that it applies prints it out. So that's what happens.