C++ vector vs. array

 

	vector	array	others
1	template class (c++ only)	built-in language construct (both c/c++)
2	dynamic arrays with list interface	statically or dynamically implemented with primitive data type	see ex.1
3	resizable	fixed size	see ex.2
4	automatically deallocated from heap memory	have to be explicitly deallocated	see ex.3
5	size can be determined in O(1)	size cannot be determined of dynamically defined
6	maintains variables keeping track of the size of container all the time	seperate parameter is also passed to the function	see ex.4
7	reallocation is done implicitly when vectors become larger than its capacity	no reallocation is done implicitly
8	can be returned from a function	cannot be returned unless dynamically allocated from a function	see ex.5 and 6
9	can be copied or assigned directly	cannot be copied or assigned directly	see ex.7

 

primitive data type is basic type or built-in type.

#include <bits/stdc++.h> 
using namespace std; 

/*ex.1*/
int main() 
{ 
	int array[100]; // Static Implementation 
	int* arr = new int[100]; // Dynamic Implementation 
	vector<int> v; // Vector's Implementation 
	return 0; 
} 

#include <bits/stdc++.h> 
using namespace std; 


/*ex.2*/
int main() 
{ 
	int array[100]; // Static Implementation 

	cout << "Size of Array " << sizeof(array) / sizeof(array[0]) << "\n"; 

	vector<int> v; // Vector's Implementation 

	// Inserting Values in Vector 
	v.push_back(1); 
	v.push_back(2); 
	v.push_back(3); 
	v.push_back(4); 
	v.push_back(5); 

	cout << "Size of vector Before Removal=" << v.size() << "\n"; 

	// Output Values of vector 
	for (auto it : v) 
		cout << it << " "; 

	v.erase(v.begin() + 2); // Remove 3rd element 

	cout << "\nSize of vector After removal=" << v.size() << "\n"; 

	// Output Values of vector 
	for (auto it : v) 
		cout << it << " "; 

	return 0; 
} 

#include <bits/stdc++.h> 
using namespace std; 

/*ex.3*/
int main() 
{ 
	int* arr = new int[100]; // Dynamic Implementation 
	delete[] arr; // array Explicitly deallocated 

	vector<int> v; // Automatic deallocation when variable goes out of scope 
	return 0; 
} 

#include <bits/stdc++.h> 
using namespace std; 

/*ex.4*/
int main() 
{ 
	int* arr = new int[100]; // Dynamic Implementation 

	cout << "Size of array= "; 
	cout << sizeof(arr) / sizeof(*arr) << "\n"; // Pointer cannot be used to get size of 
	// block pointed by it 
	return 0; 
} 

// Program to demonstrate arrays cannot be returned 
#include <bits/stdc++.h> 
using namespace std; 

/*ex.5*/
int* getValues() 
{ 

	int arr[10]; // Array defined locally 
	for (int i = 0; i < 10; i++) // Putting Values in array 
		arr[i] = i + 1; 

	return arr; // returning pointer to array 
} 

// main function 
int main() 
{ 

	int* array; // pointer of int type 

	array = getValues(); // Call function to get arr 

	for (int i = 0; i < 10; i++) { // Printing Values 
		cout << "*(array + " << i << ") : "; 
		cout << *(array + i) << endl; 
	} 

	return 0; 
} 

// Program to demonstrate vector can be returned 
#include <bits/stdc++.h> 
using namespace std; 

/*ex.6*/
// Function returning vector 
vector<int> getValues() 
{ 

	vector<int> v; // Vector defined locally 
	for (int i = 0; i < 10; i++) // Inserting values in Vector 
		v.push_back(i + 1); 

	return v; // returning pointer to array 
} 

// main function 
int main() 
{ 

	vector<int> get; 

	get = getValues(); // Call function to get v 

	// Output Values of vector 
	for (auto it : get) 
		cout << it << " "; 

	return 0; 
} 

#include <bits/stdc++.h> 
using namespace std; 

/*ex.7*/
// main function 
int main() 
{ 
	vector<int> v; // Vector defined locally 
	for (int i = 0; i < 10; i++) 
		v.push_back(i + 1); 

	vector<int> get; 

	get = v; // Copying vector v into vector get 

	cout << "vector get:\n"; 
	for (auto it : get) 
		cout << it << " "; 

	int arr[10]; 
	for (int i = 0; i < 10; i++) // Putting Values in array 
		arr[i] = i + 1; 

	int copyArr[10]; 

	copyArr = arr; // Error 

	return 0; 
} 

revised from: https://www.geeksforgeeks.org/advantages-of-vector-over-array-in-c/