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I use something like this:
map<string, Data>::iterator it = mymap->begin();
map<string, Data>::iterator end = mymap->end();
while (it != end) {
// do stuff
++it;
}
I was just wondering if this would work even if the map is empty. I couldn't find any information about the return of map::begin() if the map ist empty.
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Return value: It returns a collection view of all the values present in the map. [student 4, student 3, student 6, student 1, student 2, student 5] As you can see, the output of the above example is returning a collection view of values. So any change in the map will be reflected in the collection view automatically.
begin () function is used to return an iterator pointing to the first element of the map container. begin () function returns a bidirectional iterator to the first element of the container. mapname.begin () Parameters : No parameters are passed.
map::begin () function is an inbuilt function in C++ STL, which is defined in header file. begin () is used to access the element which is at the very beginning of the associated map container. This function returns an iterator which points to the first element of the container.
Now, map () returns a map object, which is an iterator that yields items on demand. That’s why you need to call list () to create the desired list object. For another example, say you need to convert all the items in a list from a string to an integer number. To do that, you can use map () along with int () as follows:
If the map is empty, the begin and end iterators are equal, i.e. returns mymap->end().
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