We can use the following syntax to initialize a vector.
// assume that UserType has a default constructor vector<UserType> vecCollections; Now, if UserType doesn't provide a default constructor for UserType but only a constructor as follows:
explicit UserType::UserType(int i) { ... }. How should I call this explicit element initializer with the vector constructor?
vector<UserType> vecCollections(10, UserType(2)); Unfortunately there is no way in current C++ (C++03) to initialize the vector with arbitrary elemtnts. You can initialize it with one and the same element as in @Erik's answer.
However in C++0x you can do it. It is called an initializer_list
vector<UserType> vecCollections({UserType(1), UserType(5), UserType(10)}); Incidentally, you might want to check out the boost::assign library, which is a very syntactically convenient way to assign to a vector and other containers
std::vector<char> items(10, 'A'); //initialize all 10 elements with 'A' However, if you want to initialize the vector with different values, then you can write a generic vector initializer class template, and use it everywhere:
template<typename T> struct initializer { std::vector<T> items; initializer(const T & item) { items.push_back(item); } initializer& operator()(const T & item) { items.push_back(item); return *this; } operator std::vector<T>&() { return items ; } }; int main() { std::vector<int> items(initializer<int>(1)(2)(3)(4)(5)); for (size_t i = 0 ; i < items.size() ; i++ ) std::cout << items[i] << std::endl; return 0; } Output:
1 2 3 4 5 Demo at ideone: http://ideone.com/9dODD
