vectors in cpp code example

Example 1: declare vectors c++

vector<int> vec;
//Creates an empty (size 0) vector
 

vector<int> vec(4);
//Creates a vector with 4 elements.

/*Each element is initialised to zero.
If this were a vector of strings, each
string would be empty. */

vector<int> vec(4, 42);

/*Creates a vector with 4 elements.
Each element is initialised to 42. */


vector<int> vec(4, 42);
vector<int> vec2(vec);

/*The second line creates a new vector, copying each element from the
vec into vec2. */

Example 2: vector in c++

vector<int> g1; 
  
    for (int i = 1; i <= 5; i++) 
        g1.push_back(i); 
  
    cout << "Output of begin and end: "; 
    for (auto i = g1.begin(); i != g1.end(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of cbegin and cend: "; 
    for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
        cout << *i << " "; 
  
    cout << "\nOutput of rbegin and rend: "; 
    for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
        cout << *ir << " ";

Example 3: how to use vectors c++

#include <iostream>
#include <vector>
using namespace std;

int main() {
  //vector element size
  const int size = 4; 
  //vector with int data type
  //all elements are equal to 4
  vector<int> myVect (size, 4);

  for (int i=0; i<size; i++) {
    cout << "Vector index(" << i <<") is: "<< myVect[i] << endl; 
  }
  return 0;
}

Example 4: vectors in c++

vector <int> vc;

Example 5: defining vectors in c#

var v1 = Vector.Create<double>(5);