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What is Memory Management?

Memory management is defined as the process of managing a computer’s memory, such as assigning memory to programs, variables, and so on, in such a way that it does not affect overall performance.

Need for Memory Management:

Memory management is required to ensure that no memory is wasted and that allocation occurs efficiently. The memory used by a C++ program is divided into sections. We’ll look at two of them here: stack and heap.

• Stack: All variables declared within the function, as well as other information related to the function, are stored in the stack.
• Heap: Heap is unused memory and the area from which memory is dynamically allocated when the program runs.

Allocation and Deallocation of Memory:

In C++, two operators are used to allocate and deallocate memory, namely

• new operator
• delete operator

Allocation:

Syntax:

pointer_variable = new data-type  

Deallocation:

Syntax:

delete pointer_variable;   

Example:

#include <iostream>
using namespace std;

class Test {
   public:
      Test() { 
         cout << "Constructor called!" <<endl; 
      }
      ~Test() { 
         cout << "Destructor called!" <<endl; 
      }
};
int main() {
   Test* ob = new Test[4];
   delete [] ob; // Delete array

   return 0;
}

Output:

Constructor called!
Constructor called!
Constructor called!
Constructor called!
Destructor called!
Destructor called!
Destructor called!
Destructor called!

Memory Leak:

Memory leakage occurs in C++ when programmers allocate memory with the new keyword but fail to deallocate it with the delete() function or delete[] operator. One of the most common causes of memory leakage in C++ is the use of the incorrect delete operator.

Disadvantage: If a program has memory leaks, its memory usage increases satirically because all systems have limited memory and memory is expensive. As a result, it will cause issues.

Dangling Pointer:

A dangling pointer is a pointer that points to a memory location that has been deleted (or freed). Pointer can act as a dangling pointer in three different ways.

• De-allocation of memory
• Function Call
• Variable goes out of scope

Examle:

int* fun()
{
    // x is local variable and goes out of
    // scope after an execution of fun() is
    // over.
    int x = 5;
   
    return &x;
}
int main()
{
    int *p = fun();
     //
     return 0;
}

here, p points to something which is not valid anymore.

Smart Pointer:

A Smart Pointer is a pointer wrapper class that has operators like * and -> overloaded. The smart pointer class’s objects resemble regular pointers. However, unlike Normal Pointers, it can deallocate and free destroyed object memory.

Note: also read about File Handling using File Streams in C++

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