vector initialization c++

#include <iostream>
#include <vector>
 
#define M 3
#define N 4
 
int main()
{
  // specify default value to fill the vector elements
  int default_value = 1;
  // first initialize a vector of ints with given default value
  std::vector<int> v(N, default_value);
  // Use above vector to initialize the two-dimensional vector
  std::vector<std::vector<int>> matrix(M, v);
  
  return 0;
}

// CPP program to create an empty vector 
// and push values one by one. 
#include <vector>

using namespace std;
int main() 
{ 
    // Create an empty vector 
    vector<int> vect;  
    //add/push an integer to the end of the vector
    vect.push_back(10); 
	//to traverse and print the vector from start to finish
    for (int x : vect) 
        cout << x << " ";

    return 0; 
}

// First include the vector library:
#include <vector>

// The syntax to create a vector looks like this:
std::vector<type> name;

// We can create & initialize "lol" vector with specific values:
std::vector<double> lol = {66.666, -420.69};

// it would look like this: 66.666 | -420.69

// CPP program to create an empty vector 
// and push values one by one. 
#include <bits/stdc++.h> 
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; 
} 

 vector<int> arr(10,0);

std::vector<type> name;

// CPP program to initialize a vector from 
// another vector. 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    vector<int> vect1{ 10, 20, 30 }; 
  
    vector<int> vect2(vect1.begin(), vect1.end()); 
  
    for (int x : vect2) 
        cout << x << " "; 
  
    return 0; 
} 

#include <bits/stdc++.h> 
#include <vector> 
using namespace std; 
  
int main() 
{ 
// This vector initializes with the values: 10, 20, and 30
  vector<int> vect{ 10, 20, 30 }; 

    return 0; 
} 

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. */

// CPP program to create an empty vector 
// and push values one by one. 
#include <bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    // Create an empty vector 
    vector<int> vect;  
     
    vect.push_back(10); 
    vect.push_back(20); 
    vect.push_back(30); 
  
    for (int x : vect) 
        cout << x << " "; 
  
    return 0; 
} 

//Note: any data type can be used in template.
std::vector<typename T> vectorName;