Example of using std::vector(begin, begin+size) constructor.

output.txt

Memory used after allocating lg_array: 800
Memory used after creating sm_vector: 840
sm_vector = [ 0, 1, 2, 3, 4,]
sm_vector (after modify) = [ 100, 101, 102, 103, 104,]
First 5 elements of the original lg_array = [ 0, 1, 2, 3, 4,]
size of allocation lg_array:          800
size of allocation sm_vector.data():  40

vector_begin_end_example.cxx

// I am using a library here to let me track memory allocated but that is just to show that 
// This vector constructor does actually cause new memory to be allocated and the elements are copied
#include <iostream>
#include "umpire/ResourceManager.hpp"
#include "umpire/Allocator.hpp"
#include "umpire/TypedAllocator.hpp"

int main(int, char**) {
  auto& rm = umpire::ResourceManager::getInstance();
  umpire::Allocator alloc = rm.getAllocator("HOST");
  umpire::TypedAllocator<double> vector_allocator(alloc);

  // create a double* 100 elements and fill it with 1, 2, 3...
  size_t big_sz = 100;
  double* lg_array = (double*)alloc.allocate(100*sizeof(double));

  for(size_t i = 0; i < big_sz; i++){
    lg_array[i] = 1.0 * i;
  }

  // Note the ammount of memory currently allocated
  std::cout<< "Memory used after allocating lg_array: " << alloc.getCurrentSize() << "\n";
  
  // Use the vector(begin, end) constructor (passing our custom allocator to track the allocations)
  std::vector< double, umpire::TypedAllocator<double> > sm_vector(lg_array, lg_array+5, vector_allocator);

  // Note memory for 5 more doubles has been allocated!
  std::cout<< "Memory used after creating sm_vector: " << alloc.getCurrentSize() << "\n";
  // The elements of the vector have the same value initally
  std::cout<< "sm_vector = [";
  for(auto& elm: sm_vector){
    std::cout << " "<< elm << ",";
  }
  std::cout << "]\n";

  // but if they are modified...
  for(auto&& elm: sm_vector){
    elm += 100;
  }
  std::cout << "sm_vector (after modify) = [";
  for(auto& elm: sm_vector){
    std::cout << " "<< elm << ",";
  }
  std::cout << "]\n";
  // The original elements in the lg_array are not, differnt memory no connection between the two.
  std::cout << "First 5 elements of the original lg_array = [";
  for(size_t i = 0; i < 5; i++){
    std::cout << " "<< lg_array[i] << ",";
  }
  std::cout << "]\n";
  
  std::cout << "size of allocation lg_array:          " << rm.getSize(lg_array) << "\n";
  std::cout << "size of allocation sm_vector.data():  " << rm.getSize(sm_vector.data()) << "\n";
  return 0;
}