Understanding Memory Allocation in C Programming

Slide Note
Embed
Share

This content provides insights into memory allocation in C programming. It covers concepts like malloc, calloc, free, and realloc, illustrating how memory can be dynamically allocated and deallocated. The code snippets demonstrate how to work with arrays and pointers, along with explanations on stack and heap memory. The slides present a visual guide to understanding these memory management techniques.

jakob
jakob Follow

Uploaded on Aug 05, 2024 | 0 Views

Download Presentation

Please find below an Image/Link to download the presentation.

The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.

E N D

Presentation Transcript

  1. : - 1

  2. " " , : int main() { int a[10]; ... }; 2

  3. int main() { ... printf("enter number of elements\n"); scanf("%d", &size); int a[size]; ... }; 3

  4. , " ( " heap ) 4

  5. Data data ( Stack ) Last In First Out (LIFO) Heap ) ( )! " stack ) ( heap ( ) ( 5

  6. C C malloc calloc free realloc - 0 stdlib.h 6

  7. malloc void *malloc(int nBytes) ) ( NULL 7

  8. malloc int 10 int main() { int *a = (int*) malloc(10 * sizeof(int)); ... return 0; } ) sizeof ( void* ) ( 8

  9. malloc type *var-name = (type*) malloc(amount * sizeof(type)); casting ) ( 9

  10. free void free(void *ptr) ptr - malloc, calloc - realloc ptr - 10

  11. int main() { int *a, size, i; printf("Enter array size\n"); scanf("%d", &size); a = (int*) malloc(size * sizeof(int)); if (a == NULL) return 1; for (i = 0; i < size; i++) scanf("%d", &a[i]); for (i = 0; i < size; i++) printf("%d", a[i]); free(a); return 0; } 11

  12. int main() { int *a, size, i; main a size i Stack printf("Enter array size\n"); scanf("%d", &size); a = (int*) malloc(size * sizeof(int)); if (a == NULL) return 1; for (i = 0; i < size; i++) scanf("%d", &a[i]); for (i = 0; i < size; i++) printf("%d", a[i]); Heap free(a); return 0; } 12

  13. void* calloc( unsigned int n, unsigned int size_el ) size_el n ( , , .) void* realloc( void *ptr, unsigned int size ) size NULL , 13

  14. calloc - int main() { int *a, size, i; printf("Enter array size\n"); scanf("%d", &size); a = (int*) calloc(size, sizeof(int)); if (a == NULL) return 1; size , sizeof(int) - 0 for (i = 0; i < size; i++) scanf("%d", &a[i]); for (i = 0; i < size; i++) printf("%d", a[i]); free(a); return 0; } 14

  15. realloc - int *ptr = NULL; int size = 0, new_size = 0; scanf("%d", &size); ptr = (int*) malloc( size * sizeof(int) ); /* incomplete, must check if allocation succeeded */ ... scanf("%d", &new_size); ptr = (int*) realloc( ptr, new_size*sizeof(int) ); /* incomplete, must check if allocation succeeded */ ... if (ptr != NULL) free(ptr); 15

  16. int* func() { int *memPtr = NULL; memPtr = (int*) malloc(10 * sizeof(int)); ... return memPtr; } memPtr int main() { int * ptr = func(); if (ptr != NULL) { // do something with ptr free(ptr); ptr = NULL; } } ptr 16

  17. ' : " " ' : , ' ' 17

  18. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 18

  19. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 19

  20. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 20

  21. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 21

  22. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } ? 22

  23. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 23

  24. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 24

  25. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } capacity 25

  26. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } 26

  27. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } \0 27

  28. char* readLine() { int index = 0, c, capacity = INITIAL_SIZE; char *buffer = (char*) malloc(capacity * sizeof(char)); if (buffer == NULL) return NULL; for (c = getchar(); c != '\n'; c = getchar()) { if (index == capacity 1) { buffer = (char*) realloc(buffer, capacity * INCREMENT * sizeof(char)); if (buffer == NULL) return NULL; capacity = capacity * INCREMENT * sizeof(char); } buffer[index++] = c; } buffer[index] = '\0'; return buffer; } ( ) 28

  29. readLine int main() { char *line = readLine(); if (line == NULL) { printf("Fatal error: memory allocation failed!\n"); return 1; } printf("%s\n", line); free(line); return 0; } 29

  30. readLine int main() { char *line = readLine(); if (line == NULL) { printf("Fatal error: memory allocation failed!\n"); return 1; } printf("%s\n", line); free(line); return 0; } 30

  31. readLine int main() { char *line = readLine(); if (line == NULL) { printf("Fatal error: memory allocation failed!\n"); return 1; } printf("%s\n", line); free(line); return 0; } 31

  32. readLine int main() { char *line = readLine(); if (line == NULL) { printf("Fatal error: memory allocation failed!\n"); return 1; } printf("%s\n", line); free(line); return 0; } 32

  33. readLine int main() { char *line = readLine(); if (line == NULL) { printf("Fatal error: memory allocation failed!\n"); return 1; } printf("%s\n", line); , free(line); return 0; } 33

  34. - : NULL exit -

  35. exit void exit(int status); stdlib.h

  36. exit - realloc int , void resize(int *array, int newSize) { if (array == NULL) return; array = (int*) realloc(array, newSize * sizeof(int)); if (array == NULL) { printf("Fatal error: memory allocation failed!\n"); exit(1); } } 36

  37. typedef struct { char *title, *author; } Book; Book* newBook(const char *title, const char *author) { Book *result = (Book*) malloc(sizeof(Book)); /* incomplete, must check if allocation succeeded */ result->title = strdup(title); result->author = strdup(author); /* incomplete, must check if allocation succeeded */ return result; } 37

  38. 38

  39. Command Line Arguments main - ) ( int main(int argc, char *argv[]) { } 39

  40. ? ) - main ( : argc argv[argc] == NULL argv[0] 40

  41. #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int i; for (i = 0; i < argc; i++) printf("argv[%d] = %s\n", i, argv[i]); return EXIT_SUCCESS; } 41

  42. 42

  43. NULL hello world argc 100 4 abcde argv 1 43

  44. int main(int argc, char *argv[]) { double leftOperand, rightOperand, result; char operator; /* incomplete, make sure all arguments are present */ leftOperand = atof(argv[1]); rightOperand = atof(argv[3]); operator = *argv[2]; switch (operator) { case '+': result = leftOperand + rightOperand; break; case '-': result = leftOperand - rightOperand; break; case '*': result = leftOperand * rightOperand; break; case '/': result = leftOperand / rightOperand; break; } printf("%g %c %g = %g\n", leftOperand, operator, rightOperand, result); return EXIT_SUCCESS; } 44

Related


Understanding Memory Allocation in Operating Systems

Understanding Memory Allocation in Operating Systems

mae
Understanding Memory Organization in Computers

Understanding Memory Organization in Computers

capri
Operating System: File Allocation Methods

Operating System: File Allocation Methods

amina
Understanding Memory Organization in Computers

Understanding Memory Organization in Computers

manisa
Understanding AARCH64 Linux Kernel Memory Management

Understanding AARCH64 Linux Kernel Memory Management

ziva
Understanding Cache and Virtual Memory in Computer Systems

Understanding Cache and Virtual Memory in Computer Systems

katy
Dynamic Memory Allocation in Computer Systems: An Overview

Dynamic Memory Allocation in Computer Systems: An Overview

kashton
Understanding Garbage Collection in Java Programming

Understanding Garbage Collection in Java Programming

elva
Understanding Memory Management in Operating Systems

Understanding Memory Management in Operating Systems

asriel
Understanding Memory Management Concepts at Carnegie Mellon University

Understanding Memory Management Concepts at Carnegie Mellon University

faizan
Understanding Memory Management and Swapping Techniques

Understanding Memory Management and Swapping Techniques

alijah
Understanding Dynamic Memory Allocation in C++ with Memory Diagrams

Understanding Dynamic Memory Allocation in C++ with Memory Diagrams

pay_fla
Dynamic Memory Management Overview

Dynamic Memory Management Overview

wkam
Understanding Memory Management in C Programming

Understanding Memory Management in C Programming

taan749
Understanding Dynamic Memory Allocation in Programming

Understanding Dynamic Memory Allocation in Programming

khil_41
Understanding Memory Layout and Allocation in Computer Systems at Carnegie Mellon University

Understanding Memory Layout and Allocation in Computer Systems at Carnegie Mellon University

rash_290
Dynamic Memory Allocation Strategies in CS

Dynamic Memory Allocation Strategies in CS

winiarski_a
Leveraging MPI's One-Sided Communication Interface for Shared Memory Programming

Leveraging MPI's One-Sided Communication Interface for Shared Memory Programming

jmcgl
Understanding Shared Memory, Distributed Memory, and Hybrid Distributed-Shared Memory

Understanding Shared Memory, Distributed Memory, and Hybrid Distributed-Shared Memory

benjami
Understanding Virtual Memory Concepts and Benefits

Understanding Virtual Memory Concepts and Benefits

kyde410
Understanding Virtual Memory and its Implementation

Understanding Virtual Memory and its Implementation

tian836
Understanding Garbage Collection in Programming

Understanding Garbage Collection in Programming

jan_cuy

More Related Content