how to initialize vector

1// CPP program to create an empty vector 
2// and push values one by one. 
3#include <vector>
4
5using namespace std;
6int main() 
7{ 
8    // Create an empty vector 
9    vector<int> vect;  
10    //add/push an integer to the end of the vector
11    vect.push_back(10); 
12	//to traverse and print the vector from start to finish
13    for (int x : vect) 
14        cout << x << " ";
15
16    return 0; 
17}

1#include <iostream>
2#include <vector>
3 
4#define M 3
5#define N 4
6 
7int main()
8{
9  // specify default value to fill the vector elements
10  int default_value = 1;
11  // first initialize a vector of ints with given default value
12  std::vector<int> v(N, default_value);
13  // Use above vector to initialize the two-dimensional vector
14  std::vector<std::vector<int>> matrix(M, v);
15  
16  return 0;
17}
18

1vector<int> vect{ 10, 20, 30 };

1vector<int> a;                                       // empty vector of ints
2vector<int> b (5, 10);                                // five ints with value 10
3vector<int> c (b.begin(),b.end());                     // iterating through second
4vector<int> d (c);                                   // copy of c

1// CPP program to create an empty vector
2// and push values one by one.
3#include <bits/stdc++.h>
4using namespace std;
5
6int main()
7{
8	int n = 3;
9
10	// Create a vector of size n with
11	// all values as 10.
12	vector<int> vect(n, 10);
13
14	for (int x : vect)
15		cout << x << " ";
16
17	return 0;
18}
19