What is the difference between stack and heap allocation?

In C++, memory allocation can be done using two main methods: stack allocation and heap allocation. Understanding the differences between these two methods is crucial for effective memory management in programming.

Stack Allocation

Stack allocation is a method of memory management where variables are allocated memory on the stack. The stack is a region of memory that operates in a Last In, First Out (LIFO) manner. When a function is called, memory is allocated for its local variables on the stack, and this memory is automatically reclaimed when the function returns.

Heap Allocation

Heap allocation, on the other hand, involves allocating memory on the heap, a region of memory used for dynamic memory allocation. Memory on the heap must be manually managed; you must allocate it using the new operator and free it using the delete operator. This allows for more flexible memory usage, but it also introduces the potential for memory leaks if the allocated memory is not properly released.

Key Differences

• Lifetime: Stack-allocated memory lasts only until the function exits, while heap-allocated memory persists until it is explicitly freed.
• Size Limitations: The stack has a limited size, whereas the heap can be dynamically extended until the system runs out of memory.
• Management: Stack allocation is managed automatically, whereas heap allocation requires manual management.