c++ vector initialization code example
Example 1: initialize vector of vector 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;
}
Example 2: how to create a vector in c++
// 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;
}
Example 3: c++ initialize a vector
#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;
}
Example 4: 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 5: how to initialize vector
vector<int> vect{ 10, 20, 30 };
Example 6: initialize vector c++
// 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;
}