Is there a way to generate a specific iterator in c++?  

In c++, I just find:

```cpp
std::string strHello = "Hello World";
std::string::iterator strIt = strHello.begin();
std::string::iterator strIt2 = std::find(strHello.begin(), strHello.end(), 'W');

```

Where `std::find()` will return a iterator, and `.begin()` is also iterator type. But if I want a iterator initialized will a specific value, like:

```cpp
std::string::iterator strIt3 = strHello[3];  // error

```

How can I do that?

---

Update:  

`std::string::iterator strIt3 = strHello.begin() + 3; // works well`