Memory Layout of C Program

1. Memory Layout of C

The memory layout in C programming is a fundamental concept that is crucial for understanding how memory is managed during program execution in RAM. It defines the organization and structure of memory that the C programming language uses. In this blog post, we will delve into the memory model of C programming and its functioning.

The memory model in C programming comprises four distinct segments, each serving a particular purpose and responsible for storing different types of data. These segments are:

1.1 Code Segment (.text):

The code segment, also known as the text segment, is where the compiled machine instructions of the program are stored. It contains the executable code, including functions, statements, and instructions that make up the program's logic. This segment is typically read-only and shared among multiple instances of the same program.

1.2 Data Segment :

The data segment is divided into two subsegments:

1.2.1 Initialized Data Segment (.data):

This subsegment stores initialized global and static variables. Initialized variables are those that have an explicit value assigned other than 0 during their declaration. These variables retain their values throughout the program's execution. When a variable is initialized, a memory space is allocated for it in the data segment of the program's memory.

1.2.2 Uninitialized Data Segment (.bss):

The BSS (Block Started by Symbol) segment stores uninitialized global and static variables. These variables are initialized to zero or null values by default. The BSS segment is zero-initialized by the operating system before the program starts executing. It is called "Block Started by Symbol" because the section starts with a symbol that defines the start of the block

1.2.3 Stack Segment :

The stack segment is responsible for managing function calls, local variables, and related data. It operates using a Last-In-First-Out (LIFO) mechanism, where the most recently called function occupies the top of the stack. The stack is used to store function parameters, return addresses, and local variables. It automatically grows and shrinks as functions are called and return.

1.2.4 Heap Segment :

The heap segment is the area of memory used for dynamic memory allocation. It allows programs to request memory dynamically during runtime using functions like malloc() and free(). Unlike the stack, the heap memory must be explicitly managed by the programmer. It provides flexibility in allocating and deallocating memory as needed.

Understanding the memory model in C programming is crucial for efficient memory management and avoiding issues like memory leaks and buffer overflows. By comprehending how data is organized and stored in memory, programmers can make informed decisions when designing and implementing their programs.