declare a vector of size n c++ code example

Example 1: how to initialize vector in c++ with all elements 0

vector<int> arr(10,0);

Example 2: c++ vector size

#include <vector>

int main() {
  std::vector<int> myVector = { 666, 1337, 420 };
  
  size_t size = myVector.size(); // 3
  
  myVector.push_back(399); // Add 399 to the end of the vector
  
  size = myVector.size(); // 4
}

Example 3: declare vector of size n in c++

#include <vector>

auto n = 20
// create a vector with n=20 integer elements
std::vector<int> arr(n);