Memory layout of c programming, Slides of C programming

Download Memory layout of c programming and more Slides C programming in PDF only on Docsity!

MEMORY LAYOUT OF C

PROGRAM

Bhagyashree Patra North Orissa University

CONTENTS

• Introduction
• (^) Components of a program
• (^) Memory layout
• (^) A program example
• Conclusion
• (^) References

COMPONENTS OF A PROGRAM

• (^) Functions (caller and Calle)
• (^) Local Variables
• (^) Global Variables
• (^) Static Variables
• Dynamic memory Allocation

MEMORY LAYOUT

Basically, memory layout of C program

contains five segments these are:

Text segment

Initialized data segment (DS)

Uninitialized data segment (BSS)

Stack

Heap

DATA SEGMENT

• This segment contains all the data that is required throughout program execution. In C terms, this includes all extern and static variables. This is split into two parts: Initialized Data Segment:
• (^) It contains all the initialized global and static variables.
• (^) It has read-write permission so the value of the variable of this segment can be changed at run- time.
• (^) This segment can be further classified into an initialized read-only area and initialized read-write area.

DATA SEGMENT CONT.

Unititialized data segment

• (^) It contains all uninitialized global and static

variable.

• (^) All variables in this segment initialized by the

zero(0) and pointer with the null pointer.

• (^) The program loader allocates memory for the

BSS section when it loads the program.

HEAP

• (^) It is used to allocate the memory at run

time.

• (^) The heap area begins at the end of the BSS

segment and goes to larger addresses from

there.

• (^) Heap area managed by the memory

management functions like malloc, calloc ,

free etc which may internally use the brk

and sbrk system is shared by all shared.

• (^) The heap area is shared by all shared

libraries and dynamically loaded modules in

a process.

EXAMPLE PROGRAM… #include <stdio.h> int global_initialized = 21; int global_uninitialized; int func() { int local_inside_func; int *pointer = malloc (sizeof(int)); free(pointer); } int main(int argc, char *argv[] ) { int local_inside_main; func(); return 0; } Text segment a.out Initialized variables global_initialized(21) Uninitialized variable global_uninitialized stack Main() (^) local_inside_main Func() local_inside_func heap in t in t pointer Command line arguments argv[0]^ argv[0] argv[1] argv[1] argv[n]^ argv[n]

REFERENCES

• https://www.geeksforgeeks.org
• (^) https://articleworld.com
• (^) https://tutorialpoint.com
• (^) www.thinkaloudacademy.com

Thank you

Thank youThank you