CPP

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
}

c++ initialize vector of vector with size

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

define vector with size and value c++

// CPP program to create an empty vector
// and push values one by one.
#include <iostream>
#include <vector>
using namespace std;
 
int main()
{
    int n = 3;
 
    // Create a vector of size n with
    // all values as 10.
    vector<int> vect(n, 10);
 
    for (int x : vect)
        cout << x << " ";
 
    return 0;
}

set size of a vector c++

void resize (size_type n, value_type val = value_type());

vector size c++

size() function is used to return the size of the vector container or the number of elements in the vector container.
using namespace std;
int main(){
    vector<int> myvector{ 1, 2, 3, 4, 5 };
    cout << myvector.size();
    return 0;
}
//Output = 5

set size of a vector c++

void resize (size_type n);
void resize (size_type n, const value_type& val);

c++ create vector of size

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

for(int x = 0; x < 20; ++x)
   arr[x] = x;