Dynamic Memory Allocation in Programming

Questions and Answers

What happens to the stack pointer when a function returns?

It moves to a lower memory address. (correct)

It moves to a higher memory address. (correct)

It allocates more memory for local variables.

It stays at the same memory address.

Which section of memory stores initialized global variables?

BSS Section

Data Section (correct)

Heap Section

Stack Section

What is a required action after dynamically allocating memory using malloc?

It is automatically released when the function ends.

It can be accessed directly without any precautions.

It needs to be initialized before use.

It must be explicitly deallocated with free. (correct)

Where does the machine code of a program reside after compilation?

In the Text Section. Signup and view all the answers

Which of the following correctly describes local variables within a function?

They exist only within the function's scope. Signup and view all the answers

What is the purpose of using 'malloc' in the function?

To allocate memory dynamically during program execution Signup and view all the answers

Which section of memory is responsible for storing function parameters and return addresses?

Stack Signup and view all the answers

Which statement correctly distinguishes between global and local variables?

Global variables retain their value throughout the program execution, while local variables do not. Signup and view all the answers

What is the outcome of failing to execute 'free(ptr)' after using 'malloc'?

Memory will remain allocated and potentially lead to a memory leak. Signup and view all the answers

What does the text segment of a process's memory layout contain?

Machine code instructions that the CPU executes. Signup and view all the answers

Study Notes

Process Overview

A process is an executing program, central to computational functions on a computer.
Operates as a unit of work managed by the operating system.
The program counter and processor registers reflect the process's current activity.

Memory Layout of a Process

Memory organization for processes includes several segments:
- Text Segment: Stores the program's machine code instructions.
- Stack: Contains local variables, function parameters, and return addresses.
- Data Section: Holds global variables (initialized and uninitialized).
- Heap: Used for memory dynamically allocated at runtime.

Function Calls and Memory Management

When a function is called, a stack frame is allocated for local variables and arguments.
Upon function return, the stack frame is deallocated, and the stack pointer repositions upward.
Memory allocation can occur dynamically using the malloc() function, and it should be freed with free() after use.

Global and Local Variables

Global variables exist throughout the program's execution and are stored in the data section.
Local variables are confined to the scope of functions and stored in the stack segment.

Dynamic Memory Allocation

Dynamic memory is allocated during runtime, essential for creating complex data structures.
The heap grows toward higher memory addresses, allowing for flexible memory usage.

Example Code Insights

Global variables can be initialized (stored in the data section) or uninitialized (in the BSS segment).
In the example code, a global variable global_var is initialized to 10, while local_var inside the function is initialized to 20.
Usage of dynamically allocated memory (malloc) demonstrates how the heap manages memory during program execution.

Loading and Executing Programs

Programs transition from a passive state (stored on disk) to an active state when loaded into memory and executed as a process.
Common execution methods include double-clicking the executable icon or using command-line input.
Multiple processes can run the same program independently with separate resource allocations.

Operating System Principles

Each process operates within its own virtual address space, isolating it from other processes to ensure stability and security.

Description

This quiz covers key concepts related to dynamic memory allocation, function calls, and the management of local and global variables. You will explore how data structures and objects interact during program runtime and the differences between initialized and uninitialized global data. Test your knowledge on these essential programming topics.