Questions and Answers
What happens to the stack pointer when a function returns?
Which section of memory stores initialized global variables?
What is a required action after dynamically allocating memory using malloc?
Where does the machine code of a program reside after compilation?
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Which of the following correctly describes local variables within a function?
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What is the purpose of using 'malloc' in the function?
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Which section of memory is responsible for storing function parameters and return addresses?
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Which statement correctly distinguishes between global and local variables?
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What is the outcome of failing to execute 'free(ptr)' after using 'malloc'?
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What does the text segment of a process's memory layout contain?
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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 withfree()
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, whilelocal_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.
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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.