resize vector of vectors c++ code example

Example 1: resize two dimensional vector c++

//vector<vector<int>> M;
//int m = number of rows, n = number of columns;
M.resize(m, vector<int>(n));

Example 2: 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 3: c++ vector resize

std::vector<int> vec = {1, 2, 3};
vec.resize(2); // {1, 2}
vec.resize(4); // {1, 2, 0, 0,}
vec.resize(6, 9);  // {1, 2, 0, 0, 9, 9}