Answer to Question #186212 in C++ for Ayush parashar

Question

Explain about new and delete keywords with code

Answer 1

Answer:-

Syntax to use new operator: To allocate memory of any data type, the syntax is:

pointer-variable = new data-type;

delete operator

Since it is programmer’s responsibility to deallocate dynamically allocated memory, programmers are provided delete operator by C++ language.

Syntax:

// Release memory pointed by pointer-variable
delete pointer-variable;  

$\bigstar$ C++ program to illustrate dynamic allocation

and deallocation of memory using new and delete

lets look at this example

#include <iostream>
using namespace std;

int main ()
{
	// Pointer initialization to null
	int* p = NULL;

	// Request memory for the variable
	// using new operator
	p = new(nothrow) int;
	if (!p)
		cout << "allocation of memory failed\n";
	else
	{
		// Store value at allocated address
		*p = 29;
		cout << "Value of p: " << *p << endl;
	}

	// Request block of memory
	// using new operator
	float *r = new float(75.25);

	cout << "Value of r: " << *r << endl;

	// Request block of memory of size n
	int n = 5;
	int *q = new(nothrow) int[n];

	if (!q)
		cout << "allocation of memory failed\n";
	else
	{
		for (int i = 0; i < n; i++)
			q[i] = i+1;

		cout << "Value store in block of memory: ";
		for (int i = 0; i < n; i++)
			cout << q[i] << " ";
	}

	// freed the allocated memory
	delete p;
	delete r;

	// freed the block of allocated memory
	delete[] q;

	return 0;
}