Difference Between Stack and Heap in C++

1. Introduction

In C++ programming, understanding the difference between stack and heap memory is crucial for effective memory management. The stack is a region of memory where local variables and function call information are stored, while the heap is a larger pool of memory used for dynamic memory allocation.

2. Key Points

1. Stack memory is managed automatically by the compiler.

2. Heap memory is managed by the programmer, requiring explicit allocation and deallocation.

3. Stack memory allocation is faster but limited in size.

4. Heap memory is larger but slower and more prone to fragmentation.

3. Differences

Stack Heap
Memory is managed automatically. Memory must be managed manually.
Limited memory space. More memory space available.
Faster allocation and deallocation. Slower allocation and deallocation.
Local variables and function calls. Dynamic memory allocation.

4. Example

#include <iostream>
using namespace std;

void stackAllocation() {
    int a = 10; // allocated on the stack
    cout << "Stack variable value: " << a << endl;

void heapAllocation() {
    int *p = new int(10); // allocated on the heap
    cout << "Heap variable value: " << *p << endl;
    delete p; // deallocation is necessary

int main() {

    return 0;


Stack variable value: 10
Heap variable value: 10


1. stackAllocation function demonstrates stack memory allocation where a is automatically managed.

2. heapAllocation function demonstrates heap memory allocation where p points to an integer on the heap, requiring manual deallocation.

5. When to use?

- Use stack memory for local variables and when you need quick allocation and deallocation without the overhead of manual memory management.

- Use heap memory for large data, dynamic memory allocation, or when you need memory to persist beyond the scope of a single function call.

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