Initialize a vector in C++ (5 different ways)

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; }

Output:

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; }

Output:

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; }

Output:

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; }

Output:

10 20 30