How to use the new keyword In C++
The new Keyword in C++ represents dynamic memory allocation i.e, heap memory. The code will suffer from a memory leak if the programmer does not free up the memory before exiting. This can lead to a huge problem in long-running applications or resource-constrained hardware environments.
Syntax:
int **arr=new int*[size_of_array];
Example:
C++
// c++ Program to create// vector pointer// using new keyword (dynamic array)#include <iostream>#include <vector>using namespace std;void print_vector(int** ptr, int n){ cout << "Elements are: "; // printing the values of the array for (int i = 0; i < n; i++) { cout << **(ptr + i) << " "; } cout << endl;}void remove_element(int** ptr, int* n){ int pos = *n - 1; // releasing the element from the array delete ptr[pos]; // decreasing the size of array (*n)--;}int main(){ cout << "Enter size of array: "; // declaring size of array; int n; cin >> n; // declaring dynamic array int** ptr = new int*[n]; cout << "Enter elements of array:"; // inserting elements in array for (int i = 0; i < n; i++) { // declaring a variable to store in array int a; cin >> a; // Inserting the declared variable in the array *(ptr + i) = new int(a); } cout << "Array Before removing element\n"; print_vector(ptr, n); // remove last element from array remove_element(ptr, &n); cout << "Array After removing element\n"; print_vector(ptr, n); // removing all elements of array for (int i = 0; i < n; i++) { delete ptr[i]; } // releasing array delete ptr;} |
Output:
Enter size of array: 5 Enter elements of array: 5 4 3 2 1 Array Before removing element Elements are: 5 4 3 2 1 Array After removing element Elements are: 5 4 3 2
C++ Vector of Pointers
Prerequisites
Vector of pointers are vectors that can hold multiple pointers. Each pointer within a vector of pointers points to an address storing a value. We can use the vector of pointers to manage values that are not stored in continuous memory.