questions on dynamic memory allocation in c++ code example

Example 1: c++ dynamic memory allocation exercises

#include <iostream>

int main()
{
	int *ptr = new int;
	*ptr = 4;
	std::cout << *ptr << std::endl;
	return 0;
}

Example 2: dynamic memory allocation in c++

#include <iostream>
using namespace std;

int main () {
   double* pvalue  = NULL; // Pointer initialized with null
   pvalue  = new double;   // Request memory for the variable
 
   *pvalue = 29494.99;     // Store value at allocated address
   cout << "Value of pvalue : " << *pvalue << endl;

   delete pvalue;         // free up the memory.

   return 0;
}