https://www.geeksforgeeks.org/initialize-a-vector-in-cpp-different-ways/
Following are different ways to create and initialize a vector in C++ STL
Initializing by one by one pushing values :
// CPP program to create an empty vector// and one by one push values.#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;
} |
10 20 30
Specifying size and initializing all values :
// CPP program to create an empty vector// and one by one push values.#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;
} |
Output:
10 10 10
Initializing like arrays :
// CPP program to initialize a vector like// array.#include <bits/stdc++.h>using namespace std;
int main()
{ vector<int> vect{ 10, 20, 30 };
for (int x : vect)
cout << x << " ";
return 0;
} |
10 20 30
Initializing from array :
// CPP program to initialize a vector from// array.#include <bits/stdc++.h>using namespace std;
int main()
{ int arr[] = { 10, 20, 30 };
int n = sizeof(arr) / sizeof(arr[0]);
vector<int> vect(arr, arr + n);
for (int x : vect)
cout << x << " ";
return 0;
} |
10 20 30
Initializing from another vector :
// 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(), vect.end());
for (int x : vect2)
cout << x << " ";
return 0;
} |
10 20 30