Memory Organization in C

Memory organization in C refers to how data is stored and organized in a computer's memory. Memory is typically organized into several sections, each serving a specific purpose. Here's an overview of the common memory sections in C:

1. Text (Code) Section:

The text section contains the compiled machine code of the program's instructions.

It is typically read-only, and the program's instructions are loaded here when it is executed.

Code execution starts from the first instruction in this section.

2. Data Section:

The data section is further divided into several sub-sections:

A) Global Data (Initialized Data):

This section contains global and static variables that are explicitly initialized with values.

These variables are accessible throughout the program's execution.

B) BSS (Block Started by Symbol):

The BSS section contains global and static variables that are uninitialized.

It is initialized to zero by the system when the program starts.

C) Constant Data (Read-Only Data):

This section contains constants and strings that are marked as read-only.

Attempting to modify data in this section will result in a runtime error.

3. Heap:

The heap is a region of memory used for dynamic memory allocation.

It is managed by functions like malloc, calloc, realloc, and free.

Data allocated on the heap persists until explicitly deallocated and is typically used for storing data of variable size.

4. Stack:

The stack is used for function call management and automatic (local) variable storage.

Local variables declared within a function are typically stored on the stack.

Function call information, including return addresses and parameters, is also stored on the stack.

The stack operates in a Last-In-First-Out (LIFO) manner, meaning the most recently called function is at the top.

5. Memory-Mapped I/O:

This section may include memory addresses used for communication with hardware devices and peripherals.

Access to memory-mapped I/O is typically system-specific and requires special considerations.

6. Memory Reserved for the Operating System:

Some portions of memory are reserved by the operating system itself.

These areas are typically inaccessible to user-level programs.