Stack vs Heap: Know the Difference
What exactly is a Stack?
This specific section of computer memory is used to hold the temporary variables that are created by a function when it is called. Variables are declared, saved, and initialized in the stack during a program’s execution.
It is used as temporary storage memory for data. As soon as the computing task is completed, the memory associated with the variable will be automatically wiped from the system. A large portion of the stack section consists of methods, local variables, and reference variables.
You will learn the following things in this tutorial:
What is Heap?
The heap is a type of memory used by computer languages to hold variables that are used across multiple programs. By default, all global variables are stored in the heap memory space of the computer’s memory. It is capable of supporting dynamic memory allocation.
The heap is not handled automatically for you, and it is not managed as tightly by the CPU as it could be. It’s more like a free-floating patch of recollection than anything else. The following are some of the advantages and disadvantages of employing stack:
It enables you to manage data in a Last In First Out (LIFO) manner, which is not achievable with a linked list or an array of variables.
Invoked functions keep local variables in a stack, which is automatically destroyed after they have completed their task.
When a variable is not used outside of the scope of a function, a stack is employed.
It gives you the ability to control how memory is allocated and deallocated on your computer.
Stack automatically cleans up the item.
It is difficult to corrupt.
Variables cannot be scaled in any way.
Heap has several advantages.
Key Differences between Stack and Heap
| Parameter | Stack | Heap |
|---|---|---|
| Type of data structures | A stack is a linear data structure. | Heap is a hierarchical data structure. |
| Access speed | High-speed access | Slower compared to stack |
| Space management | Space is managed efficiently by OS so memory will never become fragmented. | Heap Space is not used as efficiently. Memory can become fragmented as blocks of memory are first allocated and then freed. |
| Access | Local variables only | It allows you to access variables globally. |
| Limit of space size | Limit on stack size dependent on OS. | Does not have a specific limit on memory size. |
| Resize | Variables cannot be resized | Variables can be resized. |
| Memory Allocation | Memory is allocated in a contiguous block. | Memory is allocated in any random order. |
| Allocation and Deallocation | Automatically done by compiler instructions. | It is manually done by the programmer. |
| Deallocation | Does not require de-allocate variables. | Explicit de-allocation is needed. |
| Cost | Less | More |
| Implementation | A stack can be implemented in 3 ways simple array-based, using dynamic memory, and Linked list-based. | Heap can be implemented using an array and trees. |
| Main Issue | Shortage of memory | Memory fragmentation |
| Locality of reference | Automatic compile-time instructions. | Adequate |
| Flexibility | Fixed-size | Resizing is possible |
| Access time | Faster | Slower |
The following are the advantages and disadvantages of using heap memory:
Advantages of using Stack
Heap assists you in determining the largest and smallest number.
Garbage collection is performed on the heap memory to free up memory that has been consumed by the object.
The Priority Queue likewise makes use of the heap approach.
It gives you the ability to access variables on a global scale.
Heap does not have a limit on the amount of memory it can hold.
Advantages and drawbacks of working with stack
Disadvantages of using Stack
: The amount of RAM available in the stack is extremely limited.
Creating an excessive number of objects on the stack can raise the likelihood of a stack overflow.
It is not feasible to gain access at random.
It is possible that the variable storage will be rewritten, resulting in undefined behavior of the function or program in some cases.
The stack will be pushed outside of the memory space, which may result in an abnormal termination of the program.
Using Heap has some disadvantages.
The following are the disadvantages and cons of using Heaps memory:
When to use the Heap or stack?
It has the capability of providing the greatest amount of RAM that an operating system can supply.
It takes longer for the computer to calculate.
Because heap memory is used globally, memory management is more difficult in this type of memory.
When compared to the stack, it takes an excessive amount of time to execute.
When should you use the Heap or the Stack?
When you need to allocate a big amount of memory, you should consider using the heap. If, for example, you wish to create a large-scale array of large structures to keep a variable around for a lengthy period, you should allocate it on the heap.
If, on the other hand, you are working with relatively small variables that are only necessary until the function that uses them is active, this is not a problem. Then you’ll want to use the stack, which is both faster and simpler to use.