008_Dec14

December 14

Dynamic Memory Allocation

In C++, it allows us to allocate memory for a variable or for an array at runtime. This is called Dynamic Memory Allocation.
In this case, we use new and delete operator.
Dynamic Memory Allocation can make memory management more efficient.
For arrays, It is efficient when the time of runtime in which we dont know the size of the array until execuition.

New Operator

This operator specifies a memory allocation. If there is sufficient memeory for a new operator, initializes the memory and returns the newly allocated and initialized memory address for the pointer variable.

Syntax

pointer_variable = new data_type;

Delete Operator

The programmer must release the dynamically allocated memory after program execuition. The delete operator is responsible for freeing dynamically allocated memory.

Syntax

delete pointer_variable;

Examples

#include <iostream>
using namespace std;

int main() {
    // initializing integer pointer
    int *pointerInt;

    // initializing float pointer
    float *pointerFloat;

    // allocating dynamic memory
    pointerInt = new int;
    pointerFloat = new float;

    //assigning value
    *pointerInt = 55;
    *pointerFloat = 67.89f;

    // printing the value
    cout << "Integer Value = " << *pointerInt << endl;
    cout << "Float Value = " << *pointerFloat;

    // freeing memory allocation
    delete pointerInt;
    delete pointerFloat;

    return 0;
}

Homework

1. What do you mean by Dynamic memory allocation? Explain how we can allocate dynamic memory in an array using new and delete operator in C++.

Dynamic memory allocation is the process of assigning the memory space during the execution time or the run time.

• A dynamic array is quite similar to a regular array, but its size is modifiable during program runtime.

// an example of dynamic memory allocation in c++ using an array

#include<iostream>
using namespace std;

int main() {
	int i, n;
    
	cout << "How many numbers will you type: ";
	cin >>n;

	int *arr = new int(n);

	cout << "Enter " << n << " numbers" << endl;
	for (i = 0; i < n; i++) {
		cin >> arr[i];
	}

	cout << "You typed: ";
	for (i = 0; i < n; i++) {
		cout << arr[i] << " ";
	}

	cout << endl;

	delete [] arr;
	return 0;
}