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

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.

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]) );

If you can, use the modern C++[11,14,17,20,...] way:

std::vector<int> ints = {10, 20, 30};

The old way of looping over a variable-length array or using sizeof() is truly terrible on the eyes and completely unnecessary in terms of mental overhead. Yuck.

In C++0x you will be able to do it in the same way that you did with an array, but not in the current standard.

With only language support you can use:

int tmp[] = { 10, 20, 30 };
std::vector<int> v( tmp, tmp+3 ); // use some utility to avoid hardcoding the size here

If you can add other libraries you could try boost::assignment:

vector<int> v = list_of(10)(20)(30);

To avoid hardcoding the size of an array:

// option 1, typesafe, not a compile time constant
template <typename T, std::size_t N>
inline std::size_t size_of_array( T (&)[N] ) {
   return N;
}
// option 2, not typesafe, compile time constant
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))

// option 3, typesafe, compile time constant
template <typename T, std::size_t N>
char (&sizeof_array( T(&)[N] ))[N];    // declared, undefined
#define ARRAY_SIZE(x) sizeof(sizeof_array(x))