What is the easiest way to initialize a std::vector with hardcoded elements?

Question

I can create an array and initialize it like this:

int a[] = {10, 20, 30}; 

How do I create a std::vector and initialize it similarly elegant?

The best way I know is:

std::vector<int> ints;  ints.push_back(10); ints.push_back(20); ints.push_back(30); 

Is there a better way?

Answer 1

If your compiler supports C++11, you can simply do:

std::vector<int> v = {1, 2, 3, 4}; 

This is available in GCC as of version 4.4. Unfortunately, VC++ 2010 seems to be lagging behind in this respect.

Alternatively, the Boost.Assign library uses non-macro magic to allow the following:

#include <boost/assign/list_of.hpp> ... std::vector<int> v = boost::assign::list_of(1)(2)(3)(4); 

Or:

#include <boost/assign/std/vector.hpp> using namespace boost::assign; ... std::vector<int> v; v += 1, 2, 3, 4; 

But keep in mind that this has some overhead (basically, list_of constructs a std::deque under the hood) so for performance-critical code you'd be better off doing as Yacoby says.

Answer 2

One method would be to use the array to initialize the vector

static const int arr[] = {16,2,77,29}; vector<int> vec (arr, arr + sizeof(arr) / sizeof(arr[0]) );