Answers for "how to change vector size c++"

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.

c++ initialize vector of vector with size

vector<vector<int>> v(10, vector<int>(10));

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);