How do I pass multiple ints into a vector at once?

C++C++11VectorPush Back

C++ Problem Overview


Currently when I have to use vector.push_back() multiple times.

The code I'm currently using is

  std::vector<int> TestVector;
  TestVector.push_back(2);
  TestVector.push_back(5);
  TestVector.push_back(8);
  TestVector.push_back(11);
  TestVector.push_back(14);

Is there a way to only use vector.push_back() once and just pass multiple values into the vector?

C++ Solutions


Solution 1 - C++

You can do it with initializer list:

std::vector<unsigned int> array;

// First argument is an iterator to the element BEFORE which you will insert:
// In this case, you will insert before the end() iterator, which means appending value
// at the end of the vector.
array.insert(array.end(), { 1, 2, 3, 4, 5, 6 });

Solution 2 - C++

Try pass array to vector:

int arr[] = {2,5,8,11,14};
std::vector<int> TestVector(arr, arr+5);

You could always call std::vector::assign to assign array to vector, call std::vector::insert to add multiple arrays.

If you use C++11, you can try:

std::vector<int> v{2,5,8,11,14};

Or

 std::vector<int> v = {2,5,8,11,14};

Solution 3 - C++

You can also use vector::insert.

std::vector<int> v;
int a[5] = {2, 5, 8, 11, 14};

v.insert(v.end(), a, a+5);

Edit:

Of course, in real-world programming you should use:

v.insert(v.end(), a, a+(sizeof(a)/sizeof(a[0])));  // C++03
v.insert(v.end(), std::begin(a), std::end(a));     // C++11

Solution 4 - C++

using vector::insert (const_iterator position, initializer_list il); http://www.cplusplus.com/reference/vector/vector/insert/

#include <iostream>
#include <vector>

int main() {
  std::vector<int> vec;
  vec.insert(vec.end(),{1,2,3,4});
  return 0;
}

Solution 5 - C++

You can also use Boost.Assignment:

const list<int> primes = list_of(2)(3)(5)(7)(11);

vector<int> v; 
v += 1,2,3,4,5,6,7,8,9;

Solution 6 - C++

These are the three most straight forward methods:

  1. Initialize from an initializer list:
std::vector<int> TestVector = {2,5,8,11,14};
  1. Assign from an initializer list:
std::vector<int> TestVector;
TestVector.assign( {2,5,8,11,14} ); // overwrites TestVector
  1. Insert an initializer list at a given point:
std::vector<int> TestVector;
...
TestVector.insert(end(TestVector), {2,5,8,11,14} ); // preserves previous elements

Solution 7 - C++

Since c++17 you could use the following method:

#include <iostream>
#include <vector>

using namespace std;

vector<int> vec;
template<typename... T>
void vecPush(const T& ... x) {
    (vec.push_back(x), ...);
}

int main() {
    vecPush(4, 10, 4);
    for(const auto& a : vec)
        cout << a << " ";
    return 0;
}

Solution 8 - C++

These days (c++17) it's easy:

auto const pusher([](auto& v) noexcept
  {
    return [&](auto&& ...e)
      {
        (
          (
            v.push_back(std::forward<decltype(e)>(e))
          ),
          ...
        );
      };
  }
);

pusher(TestVector)(2, 5, 8, 11, 14);

EDIT: for the really adventurous (c++20):

template <typename F, class Tuple>
constexpr void operator|(Tuple&& t, F f)
{
  [&]<auto ...I>(std::index_sequence<I...>) noexcept(noexcept((f(std::get<I>(t)), ...)))
  {
    (f(std::get<I>(t)), ...);
  }
  (std::make_index_sequence<std::tuple_size_v<std::remove_reference_t<Tuple>>>());
}

std::forward_as_tuple(2, 5, 8, 11, 14) | [&](auto&& e){ TestVector.push_back(std::forward<decltype(e)>(e)); }

Solution 9 - C++

Yes you can, in your case:

vector<int>TestVector;`
for(int i=0;i<5;i++)
{

    TestVector.push_back(2+3*i);
    
} 

Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionElliottView Question on Stackoverflow
Solution 1 - C++KosiekView Answer on Stackoverflow
Solution 2 - C++billzView Answer on Stackoverflow
Solution 3 - C++sashoalmView Answer on Stackoverflow
Solution 4 - C++Li KuiView Answer on Stackoverflow
Solution 5 - C++zxxcView Answer on Stackoverflow
Solution 6 - C++alfCView Answer on Stackoverflow
Solution 7 - C++user13088490View Answer on Stackoverflow
Solution 8 - C++user1095108View Answer on Stackoverflow
Solution 9 - C++Probol View Answer on Stackoverflow