Memory Managment

A program stores in hard drive, executes in CPU.

Think of it like a book:

• Hard Drive = A bookshelf where the book (program) is stored when not in use.
• RAM = A desk where you place the book while reading it (temporary workspace).
• CPU = Your brain, which reads and processes the information from the book.

Types

Code Segment

• Store compiled code.
• It uses stack and heap memory.

Stack Memory

• Store global, static variable, function call
• Automatically managed(created, removed)
• Size decided at compile time
• Store data organized way

Heap Memory

• Memory allocated during program execution
• Automatically created but manually removed
• when the programs terminates, OS automatically reclaims all allocated heap
• Size decided at run time
• Store data unorganized way
• Treat like resources
• Can't directly use, you have to use pointer to use it

Comparison: Stack vs Heap

Feature	Stack Memory	Heap Memory
Creation	Automatically created	Automatically available but requires manual allocation
Deallocation	Automatic (when function exits)	Manual (using free() or delete)
Speed	Faster	Slower
Size	Limited	Large (depends on system)
Lifetime	Exists only during function execution	Persists until manually freed
Usage	Local variables, function calls	Dynamically allocated memory

• Array created in both heap(int *p=new int(5)) and stack(int arr[]={1,2,3,4,5}).
• Linkedlist created only in heap.

Allocation

Static Memory Allocation

• Memory allocated at compile time and doesn't change during program execution, deallocated automatically when program terminates.
• It is stored in the stack/data segment.
• Global variable store in data segement and local variable store in stack.

Dynamic Memory Allocation

• Memory allocated at runtime using pointers.
• It is store in the heap memory.
• Explicit deallocation requires.

Example:

int *p;  // store at stack as it is local variable
p=new int(5);  // store at heap