The allocation of memory is the crucial factor for any application.

We allocate memory for variables and objects.

We can perform memory allocation in the following two ways:

• The stack: All variable declared inside will take memory from stack.

• The heap: This will perform the allocation of memory when the program executes.

We have data type which will allocate the memory at runtime. The new keyword is used for it.

double* pvalue  = NULL; // Pointer initialized with null
pvalue  = new double;   // Request memory for the variable

double* pvalue  = NULL;
if( !(pvalue  = new double ))
{
   cout << "Error: out of memory." <<endl;
   exit(1);

}

Dynamic Memory Allocation for Arrays:

char* pvalue  = NULL;   // Pointer initialized with null
pvalue  = new char[20]; // Request memory for the variable

Dynamic Memory Allocation for Objects:

#include <iostream>
using namespace std;

class Box
{
   public:
      Box() { 
         cout << "Constructor called!" <<endl; 
      }
      ~Box() { 
         cout << "Destructor called!" <<endl; 
      }
};

int main( )
{
   Box* myBoxArray = new Box[4];

   delete [] myBoxArray; // Delete array

   return 0;
}