set size of vector c++ code example

Example 1: when a vector in c++ is resized what happens to the elements of the vector

The C++ function std::vector::resize() changes the size of vector. If n is smaller than current size then extra elements are destroyed.

If n is greater than current container size then new elements are inserted at the end of vector.

If val is specified then new elements are initialed with val.

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: vectors c++ set the size

#include <iostream>
#include <vector>

using namespace std;

int main(void) {
   vector<int> v;

   cout << "Initial vector size = " << v.size() << endl;

   v.resize(5, 10);
   cout << "Vector size after resize = " << v.size() << endl;

   cout << "Vector contains following elements" << endl;
   for (int i = 0; i < v.size(); ++i)
      cout << v[i] << endl;

   return 0;
}

Example 4: 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);

Example 5: c++ vector initialize size

vector<Entry> array(1000);//size of 1000