Does Go have an iterator datatype?

Question

How do I write Go code that can do something like a map iterator in C++?

typedef std::map<std::string, MyStruct> MyMap;
MyMap::iterator it = myMap.find("key");
if(it!=myMap.end()) {
   it->v1 = something;
   it->v2 = something;
}

Answer 1

In go, it is pretty easy to iterate over a map using the range clause.

myMap := map[string]int {"one":1, "two":2}

for key, value := range myMap {
  // Do something.
  fmt.Println(key, value)
}

Could print

one 1
two 2

Note that you iterate in an undefined order over a map, as it is backed by a hash table rather than a tree.

The go language spec describes what the range clause returns, and you can see the effective go page for some more examples.