what is dynamic memory allocation code example

Example 1: dynamic memory allocation

int *p = new int; // request memory
*p = 5; // store value

cout << *p << endl; // Output is 5

delete p; // free up the memory

cout << *p << endl; // Output is 0

Example 2: malloc in c

#include <stdlib.h>

void *malloc(size_t size);

void exemple(void)
{
  char *string;
  
  string = malloc(sizeof(char) * 5);
  if (string == NULL)
    return;
  string[0] = 'H';
  string[1] = 'e';
  string[2] = 'y';
  string[3] = '!';
  string[4] = '\0';
  printf("%s\n", string);
  free(string);
}

/// output : "Hey!"

Example 3: allocate memory c

ptr = (castType*)calloc(n, size);

Example 4: what is dynamic memory allocation in c++

In the dynamic memory allocation the memory is allocated during run time.
The space which is allocated dynamically usually placed in a program segment which is known as heap.
In this, the compiler does not need to know the size in advance.
In C++, dynamic memory allocation means performing memory allocation manually by programmer.
It is allocated on the heap and the heap is the region of a computer memory which is managed by the programmer using pointers to access the memory.
The programmers can dynamically allocate storage space while the program is running but they cannot create a new variable name.
  
Example:

Example 5: dynamic memory allocation in c++

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

Example 6: 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;
}