Dynamic Memory Allocation

Dynamic memory allocation in C++ allows memory to be allocated during program execution. It helps programs use memory efficiently according to their needs.

What is Dynamic Memory Allocation?

Dynamic memory allocation means creating memory at runtime instead of compile time. The memory is allocated from heap memory using pointers.

Why Use Dynamic Memory Allocation?

Dynamic memory allocation is useful because it:

• Allocates memory when needed
• Saves unused memory
• Supports flexible program design
• Helps manage large data dynamically

Heap Memory

Dynamic memory is stored in the heap area of memory.

Unlike stack memory, heap memory is manually managed by the programmer.

Operators Used

C++ provides:

• new → allocate memory
• delete → free memory

Allocating Single Variable

int *ptr = new int;

Assigning Value

*ptr = 100;

Example Program

#include <iostream>
using namespace std;

int main() {

    int *ptr = new int;

    *ptr = 50;

    cout << *ptr << endl;

    delete ptr;

    return 0;
}

Output

50

How Dynamic Allocation Works

1. new allocates memory in heap
2. Pointer stores memory address
3. Data is accessed using pointer
4. delete frees allocated memory

Dynamic Array Allocation

int *arr = new int[5];

This creates an array of 5 integers dynamically.

Example of Dynamic Array

#include <iostream>
using namespace std;

int main() {

    int size = 5;

    int *arr = new int[size];

    for (int i = 0; i < size; i++) {
        arr[i] = i + 1;
    }

    for (int i = 0; i < size; i++) {
        cout << arr[i] << endl;
    }

    delete[] arr;

    return 0;
}

delete vs delete[]

delete	delete[]
Used for single variable	Used for arrays
Frees one memory block	Frees multiple memory blocks

Null Pointer After Deletion

Good practice:

ptr = nullptr;

This avoids dangling pointers.

Memory Leak

A memory leak happens when allocated memory is not released.

Example of Memory Leak

int *ptr = new int;

// forgot delete

Dangling Pointer

A dangling pointer points to memory that has already been freed.

delete ptr;

After deletion:

ptr = nullptr;

Advantages of Dynamic Memory Allocation

• Flexible memory usage
• Efficient resource management
• Useful for large programs
• Supports dynamic data structures

Disadvantages

• Manual memory handling required
• Risk of memory leaks
• More complex than static memory

Why Dynamic Memory Allocation is Important

It is important because it:

• Allows efficient memory management
• Supports linked lists, trees, and graphs
• Helps build scalable applications
• Is essential for advanced programming

Real-Life Example

Think of renting rooms in a hotel:

• Rooms are booked only when needed
• Unused rooms are released later

Dynamic memory works similarly by allocating memory only when required.

Conclusion

Dynamic memory allocation in C++ allows programmers to manage memory during runtime using new and delete. It provides flexibility, efficient memory usage, and support for advanced programming concepts and data structures.