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63c648e15f004bf4898d0099

2023-02-03T05:38:06.124Z

Question from Code

v1

it does not cap the final string at maximum length of 19.

int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: greeting message name\n"); return 1; } char greeting[20]; char *name = argv[2]; // Your code goes here int len = strlen(argv[1]); int space_left = 19 - len; greeting[0] = '\0'; strncat(greeting, argv[1], 19); if (space_left > 0) { strcat(greeting, " "); space_left--; } strncat(greeting, name, space_left); printf("%s\n", greeting); return 0; }

63c648e15f004bf4898d0099

2023-02-03T05:55:34.384Z

Question from Code

v1

why does it not concatenate name into greeting at the end?

int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: greeting message name\n"); return 1; } char greeting[20]; char *name = argv[2]; // Your code goes here strcat(argv[1], " "); int len = strlen(argv[1]); int space_left = 19 - len; greeting[0] = '\0'; strncat(greeting, argv[1], 19); strncat(greeting, name, space_left); printf("%s\n", greeting); return 0; }

63c648e15f004bf4898d0099

2023-02-03T05:57:13.939Z

Question from Code

v1

Why can't I access name? When I print it out it does not print anything.

int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: greeting message name\n"); return 1; } char greeting[20]; char *name = argv[2]; // Your code goes here strcat(argv[1], " "); int len = strlen(argv[1]); int space_left = 19 - len; greeting[0] = '\0'; strncat(greeting, argv[1], 19); strncat(greeting, name, space_left); printf("%s\n", greeting); return 0; }

63c648e15f004bf4898d0099

2023-02-03T05:59:27.641Z

Question from Code

v1

Why can't I access name? When I print it out it does not print anything. I have already tried dereferencing it.

int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: greeting message name\n"); return 1; } char greeting[20]; char *name = argv[2]; // Your code goes here strcat(argv[1], " "); int len = strlen(argv[1]); int space_left = 19 - len; greeting[0] = '\0'; strncat(greeting, argv[1], 19); strncat(greeting, name, space_left); printf("%s\n", greeting); return 0; }

63c648e15f004bf4898d0099

2023-02-10T20:08:23.889Z

Question from Code

v1

what is wrong with my code?

#include <stdio.h> #include <stdlib.h> #include "bitmap.h" /* * Read in the location of the pixel array, the image width, and the image * height in the given bitmap file. */ void read_bitmap_metadata(FILE *image, int *pixel_array_offset, int *width, int *height) { fseek(image, 10, SEEK_SET); fread(pixel_array_offset, sizeof(int), 1, image); fseek(image, 18, SEEK_SET); fread(width, sizeof(int), 1, image); fseek(image, 22, SEEK_SET); fread(height, sizeof(int), 1, image); } /* * Read in pixel array by following these instructions: * * 1. First, allocate space for m `struct pixel *` values, where m is the * height of the image. Each pointer will eventually point to one row of * pixel data. * 2. For each pointer you just allocated, initialize it to point to * heap-allocated space for an entire row of pixel data. * 3. Use the given file and pixel_array_offset to initialize the actual * struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is * consistent with the bitmap file format. * NOTE: We've tested this assumption on the Teaching Lab machines, but * if you're trying to work on your own computer, we strongly recommend * checking this assumption! * 4. Return the address of the first `struct pixel *` you initialized. */ struct pixel **read_pixel_array(FILE *image, int pixel_array_offset, int width, int height) { struct pixel **p = malloc(height * sizeof(struct pixel *)); int i; fseek(image, pixel_array_offset, SEEK_SET); for (i = 0; i < height; i++) { p[i] = malloc(width * sizeof(struct pixel)); int j; for (j = 0; j < width; j++) { fread(p[i][j], 1, 3, image); fseek(image, 3, SEEK_CUR); } } return p; } /* * Print the blue, green, and red colour values of a pixel. * You don't need to change this function. */ void print_pixel(struct pixel p) { printf("(%u, %u, %u)\n", p.blue, p.green, p.red); }

63c648e15f004bf4898d0099

2023-02-10T20:09:56.832Z

Question from Code

v1

why should I use `fread(&p[i][j], 1, 3, image);` ?

#include <stdio.h> #include <stdlib.h> #include "bitmap.h" /* * Read in the location of the pixel array, the image width, and the image * height in the given bitmap file. */ void read_bitmap_metadata(FILE *image, int *pixel_array_offset, int *width, int *height) { fseek(image, 10, SEEK_SET); fread(pixel_array_offset, sizeof(int), 1, image); fseek(image, 18, SEEK_SET); fread(width, sizeof(int), 1, image); fseek(image, 22, SEEK_SET); fread(height, sizeof(int), 1, image); } /* * Read in pixel array by following these instructions: * * 1. First, allocate space for m `struct pixel *` values, where m is the * height of the image. Each pointer will eventually point to one row of * pixel data. * 2. For each pointer you just allocated, initialize it to point to * heap-allocated space for an entire row of pixel data. * 3. Use the given file and pixel_array_offset to initialize the actual * struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is * consistent with the bitmap file format. * NOTE: We've tested this assumption on the Teaching Lab machines, but * if you're trying to work on your own computer, we strongly recommend * checking this assumption! * 4. Return the address of the first `struct pixel *` you initialized. */ struct pixel **read_pixel_array(FILE *image, int pixel_array_offset, int width, int height) { struct pixel **p = malloc(height * sizeof(struct pixel *)); int i; fseek(image, pixel_array_offset, SEEK_SET); for (i = 0; i < height; i++) { p[i] = malloc(width * sizeof(struct pixel)); int j; for (j = 0; j < width; j++) { fread(p[i][j], 1, 3, image); fseek(image, 3, SEEK_CUR); } } return p; } /* * Print the blue, green, and red colour values of a pixel. * You don't need to change this function. */ void print_pixel(struct pixel p) { printf("(%u, %u, %u)\n", p.blue, p.green, p.red); }

63c648e15f004bf4898d0099

2023-02-10T20:25:48.287Z

Question from Code

v1

Is the fread and fseek part correct?

#include <stdio.h> #include <stdlib.h> #include "bitmap.h" /* * Read in the location of the pixel array, the image width, and the image * height in the given bitmap file. */ void read_bitmap_metadata(FILE *image, int *pixel_array_offset, int *width, int *height) { fseek(image, 10, SEEK_SET); fread(pixel_array_offset, sizeof(int), 1, image); fseek(image, 18, SEEK_SET); fread(width, sizeof(int), 1, image); fseek(image, 22, SEEK_SET); fread(height, sizeof(int), 1, image); } /* * Read in pixel array by following these instructions: * * 1. First, allocate space for m `struct pixel *` values, where m is the * height of the image. Each pointer will eventually point to one row of * pixel data. * 2. For each pointer you just allocated, initialize it to point to * heap-allocated space for an entire row of pixel data. * 3. Use the given file and pixel_array_offset to initialize the actual * struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is * consistent with the bitmap file format. * NOTE: We've tested this assumption on the Teaching Lab machines, but * if you're trying to work on your own computer, we strongly recommend * checking this assumption! * 4. Return the address of the first `struct pixel *` you initialized. */ struct pixel **read_pixel_array(FILE *image, int pixel_array_offset, int width, int height) { struct pixel **p = malloc(height * sizeof(struct pixel *)); int i; fseek(image, pixel_array_offset, SEEK_SET); for (i = 0; i < height; i++) { p[i] = malloc(width * sizeof(struct pixel)); int j; for (j = 0; j < width; j++) { fread(&(p[i][j].red), 1, 1, image); fseek(image, 1, SEEK_CUR); fread(&(p[i][j].blue), 1, 1, image); fseek(image, 1, SEEK_CUR); fread(&(p[i][j].green), 1, 1, image); fseek(image, 1, SEEK_CUR); } } return p; } /* * Print the blue, green, and red colour values of a pixel. * You don't need to change this function. */ void print_pixel(struct pixel p) { printf("(%u, %u, %u)\n", p.blue, p.green, p.red); }

63c648e15f004bf4898d0099

2023-02-10T20:26:09.549Z

Question from Code

v1

What's wrong with the fread and fseek part?

#include <stdio.h> #include <stdlib.h> #include "bitmap.h" /* * Read in the location of the pixel array, the image width, and the image * height in the given bitmap file. */ void read_bitmap_metadata(FILE *image, int *pixel_array_offset, int *width, int *height) { fseek(image, 10, SEEK_SET); fread(pixel_array_offset, sizeof(int), 1, image); fseek(image, 18, SEEK_SET); fread(width, sizeof(int), 1, image); fseek(image, 22, SEEK_SET); fread(height, sizeof(int), 1, image); } /* * Read in pixel array by following these instructions: * * 1. First, allocate space for m `struct pixel *` values, where m is the * height of the image. Each pointer will eventually point to one row of * pixel data. * 2. For each pointer you just allocated, initialize it to point to * heap-allocated space for an entire row of pixel data. * 3. Use the given file and pixel_array_offset to initialize the actual * struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is * consistent with the bitmap file format. * NOTE: We've tested this assumption on the Teaching Lab machines, but * if you're trying to work on your own computer, we strongly recommend * checking this assumption! * 4. Return the address of the first `struct pixel *` you initialized. */ struct pixel **read_pixel_array(FILE *image, int pixel_array_offset, int width, int height) { struct pixel **p = malloc(height * sizeof(struct pixel *)); int i; fseek(image, pixel_array_offset, SEEK_SET); for (i = 0; i < height; i++) { p[i] = malloc(width * sizeof(struct pixel)); int j; for (j = 0; j < width; j++) { fread(&(p[i][j].red), 1, 1, image); fseek(image, 1, SEEK_CUR); fread(&(p[i][j].blue), 1, 1, image); fseek(image, 1, SEEK_CUR); fread(&(p[i][j].green), 1, 1, image); fseek(image, 1, SEEK_CUR); } } return p; } /* * Print the blue, green, and red colour values of a pixel. * You don't need to change this function. */ void print_pixel(struct pixel p) { printf("(%u, %u, %u)\n", p.blue, p.green, p.red); }

63c648e15f004bf4898d0099

2023-02-12T03:35:40.698Z

Question from Code

v1

what does this output?

#define SUPERVISOR(regular) regular + 5 int main() { int regular_pay = 20; int hours_worked = 10; printf("pay is %d\n", (hours_worked * SUPERVISOR(regular_pay))); // rest omitted }

63c648e15f004bf4898d0099

2023-02-12T03:38:40.436Z

Question from Code

v1

why is the output not "pay is 250"

#define SUPERVISOR(regular) regular + 5 int main() { int regular_pay = 20; int hours_worked = 10; printf("pay is %d\n", (hours_worked * SUPERVISOR(regular_pay))); // rest omitted }

63c648e15f004bf4898d0099

2023-02-12T03:43:00.240Z

Question from Code

v1

why was the answer to this "pay is 2050"

#define SUPERVISOR(regular) regular + 5 int main() { int regular_pay = 20; int hours_worked = 10; printf("pay is %d\n", (hours_worked * SUPERVISOR(regular_pay))); // rest omitted }

63c648e15f004bf4898d0099

2023-02-12T03:43:25.896Z

Question from Code

v1

why is the output of this code "pay is 2050"

#define SUPERVISOR(regular) regular + 5 int main() { int regular_pay = 20; int hours_worked = 10; printf("pay is %d\n", (hours_worked * SUPERVISOR(regular_pay))); // rest omitted }

63c648e15f004bf4898d0099

2023-02-14T02:15:30.233Z

Question from Code

v1

what will line 2 be after pre-processing?

#define MAXNAME = 32; char name[MAXNAME];

63c648e15f004bf4898d0099

2023-02-14T02:18:56.359Z

Explain Code

v1

#define MAXNAME = 32; char name[MAXNAME];

63c648e15f004bf4898d0099

2023-02-14T02:24:18.151Z

Question from Code

v1

why is this wrong

#define MAXNAME = 32; char name[MAXNAME];

63c648e15f004bf4898d0099

2023-02-14T02:32:15.860Z

Question from Code

v1

what will this become when the program is passed through the preprocessor?

#define MAXNAME = 32; int main() { char name[MAXNAME]; }

63c648e15f004bf4898d0099

2023-02-14T04:00:58.282Z

Question from Code

v1

how do i complete this function according to the comment?

/* * Create a new user with the given name. Insert it at the tail of the list * of users whose head is pointed to by *user_ptr_add. * * Return: * - 0 if successful * - 1 if a user by this name already exists in this list * - 2 if the given name cannot fit in the 'name' array * (don't forget about the null terminator) */ int create_user(const char *name, User **user_ptr_add) { return -1; }

63c648e15f004bf4898d0099

2023-02-14T04:01:35.677Z

Question from Code

v1

Complete this function for me.

/* * Create a new user with the given name. Insert it at the tail of the list * of users whose head is pointed to by *user_ptr_add. * * Return: * - 0 if successful * - 1 if a user by this name already exists in this list * - 2 if the given name cannot fit in the 'name' array * (don't forget about the null terminator) */ int create_user(const char *name, User **user_ptr_add) { return -1; }/* * Create a new user with the given name. Insert it at the tail of the list * of users whose head is pointed to by *user_ptr_add. * * Return: * - 0 if successful * - 1 if a user by this name already exists in this list * - 2 if the given name cannot fit in the 'name' array * (don't forget about the null terminator) */ int create_user(const char *name, User **user_ptr_add) { return -1; }

63c648e15f004bf4898d0099

2023-02-14T07:02:39.052Z

Question from Code

v1

what is wrong with this code?

int create_user(const char *name, User **user_ptr_add) { if (strlen(name) + 1 > MAX_NAME) { // ??? return 2; } User *u = malloc(sizeof(User)); // Empty user list if (**user_ptr_add == NULL) { **user_ptr_add = u; } // At least 1 existing user while (**user_ptr_add.next != NULL) { user_ptr_add = **user_ptr_add.next; } return -1; }

63c648e15f004bf4898d0099

2023-02-14T21:23:22.213Z

General Question

v1

how can you check if a file exists in c?

63c648e15f004bf4898d0099

2023-02-14T21:45:18.629Z

General Question

v1

how do you append to an array where you know the size but don't know how many elements have already been filled?

63c648e15f004bf4898d0099

2023-02-14T21:50:16.038Z

General Question

v1

how do you find the first empty space in an array in c?

63c648e15f004bf4898d0099

2023-02-14T22:17:01.312Z

General Question

v1

how do you print out the contents of a text file?

63c648e15f004bf4898d0099

2023-02-14T22:49:05.343Z

General Question

v1

how do you print a time_t value?

63c648e15f004bf4898d0099

2023-02-15T00:39:43.156Z

General Question

v1

In C, when you do "int *curr = other", does this set curr to other's value, or create an alias?

63c648e15f004bf4898d0099

2023-02-15T01:30:29.995Z

Question from Code

v1

why does this only print the last friend

for (int i = 0; i < MAX_FRIENDS; i++) { if (user->friends[i] != NULL) { // Only print this pointer's corresponding friend if the pointer is not null printf("%s\n", user->friends[i]->name); } }

63c648e15f004bf4898d0099

2023-02-15T01:40:18.766Z

Question from Code

v1

why doesn't this return the user with the matching name

for (int i = 0; i < MAX_FRIENDS; i++) { if (user->friends[i] != NULL) { // Only print this pointer's corresponding friend if the pointer is not null printf("%s\n", user->friends[i]->name); } }User *find_user(const char *name, const User *head) { // First, make sure users exist if (head != NULL) { // Start from the head User *curr = (User *) head; // Traverse linked list until reaching null while (curr != NULL) { if (strcmp(curr->name, name) == 0) { // Check if the current username matches return curr; } curr = curr->next; // If not, link to next user and repeat } } return NULL; }

63c648e15f004bf4898d0099

2023-02-15T01:40:48.780Z

Question from Code

v1

why doesn't this return the user with the matching name

User *find_user(const char *name, const User *head) { // First, make sure users exist if (head != NULL) { // Start from the head User *curr = (User *) head; // Traverse linked list until reaching null while (curr != NULL) { if (strcmp(curr->name, name) == 0) { // Check if the current username matches return curr; } curr = curr->next; // If not, link to next user and repeat } } return NULL; }

63c648e15f004bf4898d0099

2023-02-15T02:23:18.666Z

Question from Code

v1

why is this getting a segmentation fault?

int make_post(const User *author, User *target, char *contents) { // Test if either author or target doesn't exist if (author == NULL || target == NULL) { return 2; } // Check if the author and target are not friends if (are_friends(author, target) == 1) { return 1; } // Create post Post *p = malloc(sizeof(Post)); // Allocate memory strcpy(p->author, author->name); // Author strcpy(p->contents, contents); // Contents time(p->date); // Date // Insert the new post at the beginning of recipient's post list p->next = target->first_post; target->first_post = p; return 0; }

63c648e15f004bf4898d0099

2023-02-15T02:23:46.079Z

Question from Code

v1

why is this getting a segmentation fault?

int make_post(const User *author, User *target, char *contents) { // Test if either author or target doesn't exist if (author == NULL || target == NULL) { return 2; } // Create post Post *p = malloc(sizeof(Post)); // Allocate memory strcpy(p->author, author->name); // Author strcpy(p->contents, contents); // Contents time(p->date); // Date // Insert the new post at the beginning of recipient's post list p->next = target->first_post; target->first_post = p; return 0; }

63c648e15f004bf4898d0099

2023-02-15T02:52:13.043Z

General Question

v1

when you use malloc to make space for a struct that contains other structs as attributes, do you also have to use malloc for those structs inside it?

63c648e15f004bf4898d0099

2023-02-15T16:55:31.418Z

Question from Code

v1

Would this code successfully free the user pointed to by tmp without breaking the linked list?

User *tmp = *curr; *curr = (*curr)->next; free(tmp);

63c648e15f004bf4898d0099

2023-02-15T16:56:00.785Z

Help Fix Code

v1

User *tmp = *curr; *curr = (*curr)->next; free(tmp);

Free the memory associated with the tmp user without breaking the linked list.

63c648e15f004bf4898d0099

2023-02-15T17:02:00.631Z

Question from Code

v1

For this struct, how would you allocate memorize to initialize a user?

typedef struct user { char name[MAX_NAME]; char profile_pic[MAX_NAME]; // This is a *filename*, not the file contents. struct post *first_post; struct user *friends[MAX_FRIENDS]; struct user *next; } User;

63c648e15f004bf4898d0099

2023-02-15T22:03:07.148Z

Question from Code

v1

when initializing a user object based on the definition in the code, do I have to malloc space for the first_post attribute or can I simply set it to null?

typedef struct user { char name[MAX_NAME]; char profile_pic[MAX_NAME]; // This is a *filename*, not the file contents. struct post *first_post; struct user *friends[MAX_FRIENDS]; struct user *next; } User; typedef struct post { char author[MAX_NAME]; char *contents; time_t *date; struct post *next; } Post;

63c648e15f004bf4898d0099

2023-02-15T22:04:01.885Z

Question from Code

v1

when initializing a new post object, why do I have to use malloc on the date attribute but not on next?

typedef struct user { char name[MAX_NAME]; char profile_pic[MAX_NAME]; // This is a *filename*, not the file contents. struct post *first_post; struct user *friends[MAX_FRIENDS]; struct user *next; } User; typedef struct post { char author[MAX_NAME]; char *contents; time_t *date; struct post *next; } Post;

63c648e15f004bf4898d0099

2023-04-04T23:02:41.221Z

General Question

v2

In C, how do i break out of two while loops at once?

63c648e15f004bf4898d0099

2023-04-05T16:12:10.896Z

General Question

v2

do we have to error check snprintf? is it a system call (or does it use system calls)? And if so, how?

63c648e15f004bf4898d0099

2023-04-05T16:13:59.462Z

General Question

v2

can you perror asprintf?

63c648e15f004bf4898d0099

2023-04-05T16:14:35.633Z

General Question

v2

can you perror snprintf?

63c648e25f004bf4898d009e

2023-01-18T03:58:03.877Z

General Question

v1

subprocess.TimeoutExpired: Command '['./phone_loop']' timed out after 2 seconds

63c648e25f004bf4898d009e

2023-01-18T03:59:09.198Z

General Question

v1

subprocess.TimeoutExpired: Command '['./phone_loop']' timed out after 2 seconds in markus test

63c648e25f004bf4898d009e

2023-01-26T00:32:09.888Z

Question from Code

v1

why is line 34 adding a huge number?

#include <stdio.h> int populate_array(int, int *); int check_sin(int *); int main() { int sin_array[9]; int sin = 820320726; populate_array(sin, sin_array); check_sin(sin_array); } int populate_array(int sin, int *sin_array) { int digits = 0; int num = sin; while (num > 0) { sin_array[9 - digits] = num % 10; num = num / 10; digits++; } if (digits != 9) { return 1; } return 0; } int check_sin(int *sin_array) { int sum = 0; for (int i = 0; i < 9; i++) { if (i % 2 == 1) { sin_array[i] *= 2; } if (sin_array[i] >= 10) { sum += (sin_array[i] % 10); sum += (sin_array[i] / 10); } else { sum += sin_array[i]; } } if (sum % 10 == 0) { return 0; } return 1; }

63c648e25f004bf4898d009e

2023-01-26T02:37:15.765Z

Help Fix Code

v1

#include <stdio.h> #include <stdlib.h> // TODO: Implement a helper named check_permissions that matches the prototype below. int check_permissions(char *, char *); int main(int argc, char** argv) { if (!(argc == 2 || argc == 3)) { fprintf(stderr, "USAGE: count_large size [permissions]\n"); return 1; } // TODO: Process command line arguments. int accepted_files; int required_size = strtol(argv[1], NULL, 10); int file_size; char* required_permissions = argv[2]; char* permissions = "---------"; // TODO: Call check_permissions as part of your solution to count the files to // compute and print the correct value. while (scanf("%10s %*d %*s %*s %d %*s %*d %*s %*s", permissions, &file_size) == 2) { if (permissions[0] == 'd' ) { } else if (argc == 3) { if (check_permissions(permissions, required_permissions) == 0 && (file_size > required_size)) { accepted_files++; } } else if (argc == 2) { if (file_size > required_size) { accepted_files++; } } } return accepted_files; } int check_permissions(char* permissions, char* required) { for (int i = 0; i < 9; i++) { if (required[i] == 'r' || required[i] == 'w' || required[i] == 'x') { if (permissions[i+1] == '-') { return 1; } } } return 0; }

count the number of files that are bigger than the entered size and also match the permissions if given

63c648e25f004bf4898d009e

2023-02-12T21:27:58.798Z

Question from Code

v1

how do i stop segmentation faults when deleting the first node in the linked list

int delete_user(const char *name, User **user_ptr_del) { if (find_user(name, *user_ptr_del) == NULL) { return 1; } User *curr = *user_ptr_del; char *friend_name; while (curr != NULL) { for (int i = 0; i < MAX_FRIENDS; i++) { friend_name = (curr->friends)[i]->name; if (friend_name != NULL) { if (strcmp(friend_name, name) == 0) { (curr->friends)[i] = NULL; } } } curr = curr->next; } curr = *user_ptr_del; //traverses curr to the node before the user to be deleted while (curr->next != NULL) { if (strcmp((curr->next)->name, name) == 0) { break; } curr = curr->next; } free(curr->next); curr->next = (curr->next)->next; return 0; }

63c648e25f004bf4898d009e

2023-02-12T21:35:21.219Z

Help Fix Code

v1

int delete_user(const char *name, User **user_ptr_del) { if (find_user(name, *user_ptr_del) == NULL) { return 1; } User *curr = *user_ptr_del; char *friend_name; while (curr != NULL) { for (int i = 0; i < MAX_FRIENDS; i++) { friend_name = (curr->friends)[i]->name; if (friend_name != NULL) { if (strcmp(friend_name, name) == 0) { (curr->friends)[i] = NULL; } } } curr = curr->next; } curr = *user_ptr_del; //traverses curr to the node before the user to be deleted while (curr->next != NULL) { if (strcmp((curr->next)->name, name) == 0) { break; } curr = curr->next; } free(curr->next); curr->next = (curr->next)->next; return 0; }

delete the node with name name from the linked list pointed to by user_ptr_del

63c648e25f004bf4898d009e

2023-03-10T02:33:36.142Z

Question from Code

v2

why is read returning 0

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #define MAXLINE 256 #define MAX_PASSWORD 10 #define SUCCESS "Password verified\n" #define INVALID "Invalid password\n" #define NO_USER "No such user\n" int main(void) { char user_id[MAXLINE]; char password[MAXLINE]; /* The user will type in a user name on one line followed by a password on the next. DO NOT add any prompts. The only output of this program will be one of the messages defined above. Please read the comments in validate carefully */ if(fgets(user_id, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } if(fgets(password, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } int status; int fd[2]; pipe(fd); pid_t ret = fork(); if (ret < 0) { perror("fork"); exit(1); } else if (ret > 0) { close(fd[0]); if (write(fd[1], user_id, MAX_PASSWORD) == -1 ) { perror("write to pipe"); } if (write(fd[1], password, MAX_PASSWORD) == -1 ) { perror("write to pipe"); } close(fd[1]); if ((ret = wait(&status)) == -1) { perror("wait"); exit(1); } if (WIFEXITED(status)) { int exit_status = WEXITSTATUS(status); if (exit_status == 0) { printf(SUCCESS); } else if (exit_status == 2) { printf(INVALID); } else if (exit_status == 3){ printf(NO_USER); } } } else { close(fd[1]); dup2(fd[0], fileno(stdin)); read(fd[0], user_id, MAX_PASSWORD); read(fd[0], password, MAX_PASSWORD); close(fd[0]); execl("./validate", "validate", user_id, password, NULL); } return 0; }

63c648e35f004bf4898d00a8

2023-01-17T17:53:12.589Z

General Question

v1

what is the data type of a string in c

63c648e35f004bf4898d00a8

2023-01-17T17:54:25.439Z

General Question

v1

what is the type of string in C

63c648e35f004bf4898d00a8

2023-01-17T17:57:14.982Z

General Question

v1

array of characters data type in c

63c648e35f004bf4898d00ad

2023-01-29T09:15:41.582Z

Help Fix Code

v1

#include <stdio.h> #include <stdlib.h> // Implement a helper named check_permissions that matches the prototype below. int check_permissions(char *input, char *required) { for (int i = 0; i < 9; i++) { if (required[i] != '-' && input[i] != required[i]) { return 1; } } return 0; } int main(int argc, char** argv) { if (!(argc == 2 || argc == 3)) { fprintf(stderr, "USAGE: count_large size [permissions]\n"); return 1; } // Process command line arguments. int result = 2; char permission[32]; int size; int sum = 0; scanf("%*s %*s"); if (argc == 2) { while (result == 2) { result = scanf("%s %*s %*s %*s %d %*s %*s %*s %*s", permission, &size); if (size > strtol(argv[1], NULL, 10)) { sum += 1; } } printf("%d\n", sum); } else { while (result == 2) { result = scanf("%s %*s %*s %*s %d %*s %*s %*s %*s", permission, &size); // Call check_permissions as part of your solution to count the files to // compute and print the correct value. if (check_permissions(permission, argv[2]) == 0 && size > strtol(argv[1], NULL, 10)) { sum += 1; } } printf("%d\n", sum); } return 0; }

inspect the output from the ls -l command and print the number of files larger than a specified size

63c648e35f004bf4898d00ad

2023-01-29T09:20:36.900Z

Help Fix Code

v1

#include <stdio.h> #include <stdlib.h> // Implement a helper named check_permissions that matches the prototype below. int check_permissions(char *input, char *required) { for (int i = 0; i < 9; i++) { if (required[i] != '-' && input[i] != required[i]) { return 1; } } return 0; } int main(int argc, char** argv) { if (!(argc == 2 || argc == 3)) { fprintf(stderr, "USAGE: count_large size [permissions]\n"); return 1; } // Process command line arguments. int result = 2; char permission[32]; int size; int sum = 0; scanf("%*s %*s"); if (argc == 2) { while (result == 2) { result = scanf("%s %*s %*s %*s %d %*s %*s %*s %*s", permission, &size); if (size > strtol(argv[1], NULL, 10)) { sum += 1; } } printf("%d\n", sum); } else { while (result == 2) { result = scanf("%s %*s %*s %*s %d %*s %*s %*s %*s", permission, &size); // Call check_permissions as part of your solution to count the files to // compute and print the correct value. if (check_permissions(permission, argv[2]) == 0 && size > strtol(argv[1], NULL, 10)) { sum += 1; } } printf("%d\n", sum); } return 0; }

inspect the output from the ls -l command and print the number of files larger than a specified size program prints to standard output the number of regular files in the input listing that are larger than the cutoff size supplied by the user in the first command-line argument. Directories are not considered to be regular files. Do not print any extra text, just the number followed by a newline character \n.

63c648e35f004bf4898d00ad

2023-02-13T09:00:36.660Z

Help Fix Code

v1

int main() { int *data; printf("data %s\n", data); return 0; }

print data

63c648e55f004bf4898d00bc

2023-01-19T03:04:01.239Z

Question from Code

v1

what is wrong

int sum_card(int **score_card, int size) { // TODO: write the body of sum_card according to its description. int i; int sum = 0; for(i = 0, i < size, i++) { sum += score_card[i]; } return sum;

63c648e55f004bf4898d00bc

2023-01-22T02:12:43.777Z

Question from Code

v1

trying to turn int into array of int, but it doesn't seem to be working

int populate_array(int sin, int *sin_array) { for(int i = 8; i >= 0; i--){ if(sin == 0){ return 1; } else{ sin_array[i] = sin%10; sin = sin/10; } } return 0; }

63c648e55f004bf4898d00bc

2023-01-25T20:46:03.908Z

Question from Code

v1

got a segmentation error for all c greater than 2, what is wrong

void fib(int **fib_seq, int c){ *fib_seq = malloc(c*sizeof(int)); fib_seq[0] = 0; if(c >= 2){ *fib_seq[1] = 1; } if(c >= 3){ for(int i = 2; i < c; i++){ *fib_seq[i] = *fib_seq[i-1] + *fib_seq[i-2]; } } } int main(int argc, char **argv) { /* do not change this main function */ int count = strtol(argv[1], NULL, 10); int *fib_sequence; fib(&fib_sequence, count); for (int i = 0; i < count; i++) { printf("%d ", fib_sequence[i]); } free(fib_sequence); return 0; }

63c648e55f004bf4898d00bc

2023-01-25T20:52:13.429Z

Help Fix Code

v1

void fib(int **fib_seq, int c){ *fib_seq = malloc(c*sizeof(int)); *fib_seq[0] = 0; if(c >= 2){ *fib_seq[1] = 1; } if(c >= 3){ for(int i = 2; i < c; i++){ *fib_seq[i] = *fib_seq[i-1] + *fib_seq[i-2]; } } } int main(int argc, char **argv) { /* do not change this main function */ int count = strtol(argv[1], NULL, 10); int *fib_sequence; fib(&fib_sequence, count); for (int i = 0; i < count; i++) { printf("%d ", fib_sequence[i]); } free(fib_sequence); return 0; }

got a segmentation error for all c greater than 2, what is wrong

63c648e55f004bf4898d00bc

2023-01-25T22:18:40.685Z

Help Fix Code

v1

int **split_array(const int *s, int length) { int size1; int size2; if (length%2 == 0){ size1 = size2 = length/2; } else{ size1 = length/2 + 1; size2 = length/2; } int *arr1 = malloc(sizeof(int)*size1); int *arr2 = malloc(sizeof(int)*size2); for(int i = 0; i < length; i++){ if (i%2==0){ arr1[i] = s[i]; } else{ arr2[i] = s[i]; } } int **arr3 = malloc(sizeof(int)*length); arr3 = {arr1, arr2}; return arr3; }

how do I initialize array of array using malloc

63c648e55f004bf4898d00bc

2023-01-25T22:25:55.907Z

Help Fix Code

v1

int **split_array(const int *s, int length) { int size1; int size2; if (length%2 == 0){ size1 = size2 = length/2; } else{ size1 = length/2 + 1; size2 = length/2; } int *arr1 = malloc(sizeof(int)*size1); int *arr2 = malloc(sizeof(int)*size2); for(int i = 0; i < length; i++){ if (i%2==0){ arr1[i] = s[i]; } else{ arr2[i] = s[i]; } } int **arr3 = malloc(sizeof(int*)*2); arr3[0] = arr1; arr3[1] = arr2; return arr3; }

it is suppose to split an array into 2 arrays

63c648e55f004bf4898d00bc

2023-01-25T22:39:23.558Z

Help Fix Code

v1

int **split_array(const int *s, int length) { int size1; int size2; if (length%2 == 0){ size1 = size2 = length/2; } else{ size1 = length/2 + 1; size2 = length/2; } int *arr1 = malloc(sizeof(int)*size1); int *arr2 = malloc(sizeof(int)*size2); for(int i = 0; i < length; i++){ if (i%2==0){ arr1[i/2] = s[i]; } else{ arr2[i/2] = s[i]; } } int **arr3 = malloc(sizeof(int*)*2); arr3[0] = arr1; arr3[1] = arr2; return arr3; }

it is suppose to split an array into 2 arrays

63c648e55f004bf4898d00bc

2023-01-25T22:49:38.099Z

Help Fix Code

v1

int *build_array(char **strs, int size) { int *arr = malloc(size*sizeof(int)); for(int i = 0; i < size; i++){ arr[i] = strtol(strs[i], NULL, 10); } return arr; }

suppose to convert str into array of int

63c648e55f004bf4898d00bc

2023-01-27T01:23:42.719Z

Help Fix Code

v1

char *cop = "tiramisu"; strncpy(sweet, cop, sizeof(*sweet)); *sweet[8] = "\0";

The string sweet has been declared on the heap and has space for 20 characters. Set the value of sweet to "tiramisu" without changing its address.

63c648e55f004bf4898d00bc

2023-01-27T01:25:32.807Z

Help Fix Code

v1

int main() { char *sweet = malloc(20 * sizeof(char)); // Submitted code below char *cop = "tiramisu"; strncpy(sweet, cop, sizeof(*sweet)); sweet[8] = "\0"; // Submitted code above /* hidden test code */ return 0; }

The string sweet has been declared on the heap and has space for 20 characters. Set the value of sweet to "tiramisu" without changing its address.

63c648e55f004bf4898d00bc

2023-01-27T02:07:39.640Z

Help Fix Code

v1

void update_contact(struct contact *c, char name, int num, char add){ strcpy((*c).name, name); (*c).num = num; strcpy((*c).address, add); }

Given the following program, write the function update_contact which takes a pointer to the struct contact, a new name, a new number, and a new address to change the struct’s members. Look at the function call for the order of arguments and appropriate types.

63c648e55f004bf4898d00bc

2023-01-27T05:40:51.677Z

Help Fix Code

v1

struct node { int value; struct node *next; }

Create a node struct with the following struct members: - value, an integer - next, a pointer to another node

63c648e55f004bf4898d00bc

2023-01-27T05:41:59.473Z

Help Fix Code

v1

struct node { int value; struct node *next; };

Create a node struct with the following struct members: - value, an integer - next, a pointer to another node Typedef your structure as Node.

63c648e55f004bf4898d00bc

2023-02-02T23:21:22.016Z

Help Fix Code

v1

int truncate(char *s, int n){ if (strlen(s) <= n){ return 0; } else{ s[n] = "\0"; int result = strlen(s) - n; return result; } }

truncate string

63c648e55f004bf4898d00bc

2023-02-02T23:30:43.704Z

Help Fix Code

v1

int truncate(char *s, int n){ if (strlen(s) <= n){ return 0; } else{ s[n] = "\0"; int result = strlen(s) - n; return result; } }

s[n] = "\0" is not working

63c648e55f004bf4898d00bc

2023-02-03T01:29:17.419Z

Help Fix Code

v1

int truncate(char *s, int n){ int len = strlen(s); printf("%d", len); if (len <= n){ return 0; } else{ s[n] = '\0'; return (len-n); } }

Write a function named truncate() that takes a string s and a non-negative integer n. If s has more than n characters (not including the null terminator), the function should truncate s at n characters and return the number of characters that were removed. If s has n or fewer characters, s is unchanged and the function returns 0. For example, if s is the string "function" and n is 3, then truncate() changes s to the string "fun" and returns 5.

63c648e55f004bf4898d00bc

2023-02-03T01:30:10.389Z

Help Fix Code

v1

int truncate(char *s, int n){ int len = strlen(s); if (len <= n){ return 0; } else{ s[n] = '\0'; return (len-n); } }

strlen is does not return the actual size of the string in int, what should i do

63c648e55f004bf4898d00bc

2023-02-03T03:29:16.638Z

Help Fix Code

v1

int strip_q_marks(char *s){ int length = strlen(s); for (int i = length-1; i <= 0; i--){ if (s[i] != '?'){ s[i+1] = '\0'; return i+1; } } return 0; }

strip the ? at the end of the string and return the amount of ? stripped

63c648e55f004bf4898d00bc

2023-02-05T00:52:56.740Z

Help Fix Code

v1

int create_user(const char *name, User **user_ptr_add) { if (strlen(name) >= MAX_NAME - 1){ //checks if name is over 32-1 characters (-1 reserved for null terminator) return 2; } User *curr_user = *user_ptr_add; while (curr_user != NULL){ //goes through the linked list and search for users with the same name curr_user = curr_user->next; if (strcmp(curr_user->name, name)==0){ //if a user has the same name as the requested new user, return 1 return 1; } } User *new_user = (User*) malloc(sizeof(User)); if(new_user == NULL){ //if malloc fails, it will return -1; return -1; } strcpy(new_user->name, name); //initializing the user's strcpy(new_user->profile_pic, ""); new_user->first_post = NULL; memset(new_user->friends, 0, sizeof(new_user->friends)); //set all the pointers in the friend array to NULL new_user->next = NULL; User *curr_user2 = *user_ptr_add; if (curr_user2 == NULL){ curr_user2 = new_user; } else{ while (curr_user2 != NULL){ curr_user2 = curr_user2->next; } curr_user2 = new_user; } return 0; }

* Create a new user with the given name. Insert it at the tail of the list * of users whose head is pointed to by *user_ptr_add. * * Return: * - -1 if malloc fails * - 0 if successful * - 1 if a user by this name already exists in this list * - 2 if the given name cannot fit in the 'name' array * (don't forget about the null terminator) */

63c648e55f004bf4898d00bc

2023-02-05T01:18:25.567Z

Help Fix Code

v1

int create_user(const char *name, User **user_ptr_add) { if (strlen(name) >= MAX_NAME - 1){ //checks if name is over 32-1 characters (-1 reserved for null terminator) return 2; } User *curr_user = *user_ptr_add; while (curr_user != NULL){ //goes through the linked list and search for users with the same name curr_user = curr_user->next; if (strcmp(curr_user->name, name)==0){ //if a user has the same name as the requested new user, return 1 return 1; } } User *new_user = (User*) malloc(sizeof(User)); if(new_user == NULL){ //if malloc fails, it will return -1; return -1; } strcpy(new_user->name, name); //initializing the user's strcpy(new_user->profile_pic, ""); new_user->first_post = NULL; memset(new_user->friends, 0, sizeof(new_user->friends)); //set all the pointers in the friend array to NULL new_user->next = NULL; if (*user_ptr_add == NULL){ *user_ptr_add = new_user; } else{ User *curr_user2 = *user_ptr_add; while (curr_user2->next != NULL){ curr_user2 = curr_user2->next; } curr_user2->next = new_user; } return 0; }

getting segmentation error

63c648e55f004bf4898d00bc

2023-03-09T05:33:01.752Z

Help Fix Code

v1

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #define MAXLINE 256 #define MAX_PASSWORD 10 #define SUCCESS "Password verified\n" #define INVALID "Invalid password\n" #define NO_USER "No such user\n" int main(void) { char user_id[MAXLINE]; char password[MAXLINE]; /* The user will type in a user name on one line followed by a password on the next. DO NOT add any prompts. The only output of this program will be one of the messages defined above. Please read the comments in validate carefully */ if(fgets(user_id, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } if(fgets(password, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } if (strlen(user_id) > MAX_PASSWORD || strlen(password) > MAX_PASSWORD) { fprintf(stderr, "Error: User id or password is too long"); exit(1); } int fd[2]; if (pipe(fd) == -1){ perror("pipe"); exit(1); } int r = fork(); if (r == -1){ perror("fork"); exit(1); } else if (r == 0){ close(fd[1]); if (dup2(fd[0], STDIN_FILENO) == -1){ perror("dup2"); exit(1); } execl("./validate", "validate", NULL); perror("execl"); exit(1); } else{ if (close(fd[1] == -1)){ perror("close"); exit(1); } char result[MAX_PASSWORD]; if (read(fd[0], result, MAX_PASSWORD) == -1){ perror("close"); exit(1); } int status; if (wait(&status) == -1){ perror("wait"); exit(1); } if (WIFEXITED(status)) { int exit_status = WEXITSTATUS(status); if (exit_status == 0) { printf(SUCCESS); } else if (exit_status == 2) { printf(INVALID); } else { printf(NO_USER); } } } return 0; }

pipe input to another program

63c648e55f004bf4898d00bc

2023-03-14T04:21:34.232Z

Help Fix Code

v2

create a linkedlist for makefile

Rule *parse_file(FILE *fp) { Rule *rules = NULL; Rule *current_rule = NULL; char line[256]; while (fgets(line, sizeof(line), fp)) { if (is_comment_or_empty(line) == 1 && line[0] != '\n') { continue; // Skip comments and empty lines } // Remove the newline character at the end of the line line[strcspn(line, "\n")] = '\0'; if (line[0] == '\t') { // This is an action line Action *action = malloc(sizeof(Action)); char *token = strtok(line, " "); int argc = 0; while (token != NULL) { strcpy(action->args[argc], token); argc++; token = strtok(NULL, " "); } action->args[argc] = NULL; action->next_act = current_rule->actions; current_rule->actions = action; } else { // This is a rule line char *target = strtok(line, " "); Dependency *deps = NULL; char *dep = strtok(NULL, " "); while (dep != NULL) { Dependency *new_dep = malloc(sizeof(Dependency)); new_dep->rule = NULL; new_dep->next_dep = deps; deps = new_dep; dep = strtok(NULL, " "); } Rule *rule = malloc(sizeof(Rule)); strcpy(rule->target, target); rule->dependencies = deps; rule->actions = NULL; rule->next_rule = rules; rules = rule; current_rule = rule; } } return rules; }

63c648e55f004bf4898d00bc

2023-03-14T06:46:06.201Z

Help Fix Code

v2

getting segmentation error

Rule *parse_file(FILE *fp) { Rule *rules = NULL; Rule *current_rule = NULL; char line[256]; while (fgets(line, sizeof(line), fp)) { if (is_comment_or_empty(line) == 1) { continue; } if (line[0] != '\n' && line[0] != '\r') { line[strlen(line)-1] = '\0'; if (line[0] == '\t') { // This is an action line Action *action = malloc(sizeof(Action)); char *token = strtok(line+1, " "); int argc = 0; while (token != NULL) { action->args[argc] = strdup(token); argc++; token = strtok(NULL, " "); } action->args[argc] = NULL; action->next_act = current_rule->actions; current_rule->actions = action; } else { // This is a rule line char *target = strtok(line, " "); Dependency *deps = NULL; strtok(NULL, " "); char *dep = strtok(NULL, " "); while (dep != NULL) { Dependency *new_dep = malloc(sizeof(Dependency)); new_dep->rule = NULL; new_dep->next_dep = deps; deps = new_dep; dep = strtok(NULL, " "); } Rule *rule = malloc(sizeof(Rule)); rule->target = strdup(target); rule->dependencies = deps; rule->actions = NULL; rule->next_rule = rules; rules = rule; current_rule = rule; } } } return rules; }

63c648e55f004bf4898d00bc

2023-03-14T07:05:02.535Z

Help Write Code

v2

how do I assign a string literal with char **arg

63c648e55f004bf4898d00bc

2023-03-14T07:10:48.474Z

Help Write Code

v2

typedef struct action_node { char **args; // An array of strings suitable to be passed to execvp struct action_node *next_act; } Action; how do I assign values to a Action->args

63c648e55f004bf4898d00bc

2023-03-14T07:44:21.558Z

Help Fix Code

v2

getting corrupted top size error

Rule *parse_file(FILE *fp) { Rule *rules = NULL; Rule *current_rule = NULL; char line[MAXLINE]; while (fgets(line, sizeof(line), fp)) { if (is_comment_or_empty(line) == 1) { continue; } if (line[0] != '\n' && line[0] != '\r') { line[strlen(line)-1] = '\0'; if (line[0] == '\t') { // This is an action line Action *action = malloc(sizeof(Action)); char *token = strtok(line+1, " "); int argc = 0; while (token != NULL) { action->args = malloc(sizeof(char *)); action->args[argc] = strdup(token); //action->args[argc] = strdup(token); argc++; token = strtok(NULL, " "); } action->args[argc] = NULL; action->next_act = current_rule->actions; current_rule->actions = action; } else { // This is a rule line char *target = strtok(line, " "); Dependency *deps = NULL; strtok(NULL, " "); char *dep = strtok(NULL, " "); while (dep != NULL) { Dependency *new_dep = malloc(sizeof(Dependency)); new_dep->rule = NULL; new_dep->next_dep = deps; deps = new_dep; dep = strtok(NULL, " "); } Rule *rule = malloc(sizeof(Rule)); rule->target = strdup(target); rule->dependencies = deps; rule->actions = NULL; rule->next_rule = rules; rules = rule; current_rule = rule; } } } return rules; }

63c648e55f004bf4898d00bc

2023-03-15T04:42:56.381Z

Explain Code

v2

void run_make(char* target, Rule* rules, int pflag) { Rule* target_rule = NULL; target_rule = rules; } else { int check_target = 0; Rule* curr_rule = rules; while (curr_rule != NULL) { if (strcmp(curr_rule->target, target) == 0) { target_rule = curr_rule; check_target = 1; break; } curr_rule = curr_rule->next_rule; } if (check_target == 0 && target != NULL) { fprintf(stderr, "Error: no rule found for target '%s'\n", target); exit(1); } } int check_update; if (target_rule->dependencies != NULL) { Dependency* curr_dep = target_rule->dependencies; while (curr_dep != NULL) { Rule* curr_rule2 = rules; int dependency_is_target = 0; if (strcmp(curr_dep->rule->target, curr_rule2->target) == 0) { dependency_is_target = 1; break; } curr_rule2 = curr_rule2->next_rule; } if (dependency_is_target == 0) { curr_dep = curr_dep->next_dep; continue; } if (pflag == 0) { run_make(curr_dep->rule->target, rules, pflag); } else { int rp = fork(); if (rp == 0) { run_make(curr_dep->rule->target, rules, pflag); exit(0); } else if (rp < 0) { perror("fork"); exit(1); } } curr_dep = curr_dep->next_dep; } if (pflag == 1) { int p_status; while (wait(&p_status) > 0) { if (!WIFEXITED(p_status) || WEXITSTATUS(p_status) != 0) { exit(1); } } }

63c648e55f004bf4898d00bc

2023-03-16T22:15:35.416Z

Help Fix Code

v2

suppose to set up a timer, but doesn't work

/* The purpose of this program is to practice writing signal handling * functions and observing the behaviour of signals. */ #include <stdio.h> #include <signal.h> #include <stdlib.h> #include <unistd.h> #include <sys/time.h> /* Message to print in the signal handling function. */ #define MESSAGE "%ld reads were done in %ld seconds.\n" /* Global variables to store number of read operations and seconds elapsed. */ long num_reads, seconds; /* The first command-line argument is the number of seconds to set a timer to run. * The second argument is the name of a binary file containing 100 ints. * Assume both of these arguments are correct. */ void handler (int sig) { fprintf(stderr, MESSAGE, num_reads, seconds); exit(0); } int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: time_reads s filename\n"); exit(1); } seconds = strtol(argv[1], NULL, 10); FILE *fp; if ((fp = fopen(argv[2], "r")) == NULL) { perror("fopen"); exit(1); } struct sigaction act; act.sa_handler = handler; act.sa_flags = 0; sigemptyset(&act.sa_mask); sigaction(SIGPROF, &act, NULL); struct itimerval timer; timer.it_interval.tv_sec = 0; timer.it_interval.tv_usec = 0; timer.it_value.tv_sec = seconds; timer.it_value.tv_usec = 0; setitimer(ITIMER_PROF, &timer, NULL); /* In an infinite loop, read an int from a random location in the file, * and print it to stderr. */ for (;;) { int num; long offset = rand() % (400); fseek(fp, offset * sizeof(int), SEEK_SET); fread(&num, sizeof(int), 1, fp); fprintf(stderr, "%d\n", num); num_reads++; } return 1; // something is wrong if we ever get here! }

63c648e65f004bf4898d00c6

2023-01-27T19:42:35.977Z

General Question

v1

scanf optional *

63c648e85f004bf4898d00d5

2023-01-17T22:46:05.216Z

Explain Code

v1

num = input() for i in range(2, num): if (num % i == 0): return False return True

63c648e85f004bf4898d00da

2023-01-18T01:51:13.617Z

Explain Code

v1

int main(){ return 0; }

63c648e85f004bf4898d00da

2023-02-10T00:51:51.116Z

Explain Code

v1

char *section; while (fread(section, sizeof(char), rodata_size, file)){ printf("%s\n", section); section = NULL; }

63c648e85f004bf4898d00da

2023-02-14T05:22:49.057Z

Explain Code

v1

#define SUPERVISOR(regular) regular + 5 int main() { int regular_pay = 20; int hours_worked = 10; printf("pay is %d\n", (hours_worked * SUPERVISOR(regular_pay))); // rest omitted }

63c648e85f004bf4898d00da

2023-03-03T16:37:03.356Z

Explain Code

v1

int main(int argc, char **argv) { if (argc != 2) { fprintf(stderr, "Usage: forkloop <iterations>\n"); exit(1); } int iterations = strtol(argv[1], NULL, 10); int n = 1; for (int i = 0; i < iterations; i++) { if (n > 0){ int n = fork(); if (n < 0) { perror("fork"); exit(1); } } printf("ppid = %d, pid = %d, i = %d\n", getppid(), getpid(), i); } return 0; }

63c648e85f004bf4898d00da

2023-03-09T04:44:30.560Z

Question from Code

v1

are there two things written to the pipe?

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> // remove errno import #define MAXLINE 256 #define SUCCESS "Password verified\n" #define INVALID "Invalid password\n" #define NO_USER "No such user\n" int main(void) { char user_id[MAXLINE]; char password[MAXLINE]; /* The user will type in a user name on one line followed by a password on the next. DO NOT add any prompts. The only output of this program will be one of the messages defined above. Please read the comments in validate carefully */ if(fgets(user_id, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } if(fgets(password, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } //user_id[strcspn(user_id, "\n\r")] = '\0'; //password[strcspn(password, "\n\r")] = '\0'; printf("%s %s\n", user_id, password); // TODO int fd[2]; if (pipe(fd) == -1){ perror("pipe\n"); } int n = fork(); // parent process if (n > 0){ close(fd[0]); // write username to pipe if (write(fd[1], user_id, MAXLINE/2) == -1){ perror("write to pipe\n"); } // write password to pipe if (write(fd[1], password, MAXLINE/2) == -1){ perror("write to pipe\n"); } close(fd[1]); printf("made it to wait\n"); int status; if (wait(&status) == -1){ perror("wait\n"); } // child terminated if (WIFEXITED(status)){ int child_status = WEXITSTATUS(status); if (child_status == 0){ printf("%s", SUCCESS); } else if (child_status == 2){ printf("%s", INVALID); } else if (child_status == 3){ printf("%s", NO_USER); } // else: error } } // child process else if (n == 0) { // close the write file descriptor close(fd[1]); printf("made it to child process\n"); char *username_password[] = {"./validate", NULL}; dup2(fd[0], fileno(stdin)); execl("./validate", "validate", NULL); close(fd[0]); perror("exec\n"); exit(1); } else { perror("fork\n"); exit(1); } return 0; }

63c648e85f004bf4898d00da

2023-03-09T04:45:29.208Z

Explain Code

v1

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> // remove errno import #define MAXLINE 256 #define SUCCESS "Password verified\n" #define INVALID "Invalid password\n" #define NO_USER "No such user\n" int main(void) { char user_id[MAXLINE]; char password[MAXLINE]; /* The user will type in a user name on one line followed by a password on the next. DO NOT add any prompts. The only output of this program will be one of the messages defined above. Please read the comments in validate carefully */ if(fgets(user_id, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } if(fgets(password, MAXLINE, stdin) == NULL) { perror("fgets"); exit(1); } //user_id[strcspn(user_id, "\n\r")] = '\0'; //password[strcspn(password, "\n\r")] = '\0'; printf("%s %s\n", user_id, password); // TODO int fd[2]; if (pipe(fd) == -1){ perror("pipe\n"); } int n = fork(); // parent process if (n > 0){ close(fd[0]); // write username to pipe if (write(fd[1], user_id, MAXLINE/2) == -1){ perror("write to pipe\n"); } // write password to pipe if (write(fd[1], password, MAXLINE/2) == -1){ perror("write to pipe\n"); } close(fd[1]); printf("made it to wait\n"); int status; if (wait(&status) == -1){ perror("wait\n"); } // child terminated if (WIFEXITED(status)){ int child_status = WEXITSTATUS(status); if (child_status == 0){ printf("%s", SUCCESS); } else if (child_status == 2){ printf("%s", INVALID); } else if (child_status == 3){ printf("%s", NO_USER); } // else: error } } // child process else if (n == 0) { // close the write file descriptor close(fd[1]); printf("made it to child process\n"); char *username_password[] = {"./validate", NULL}; dup2(fd[0], fileno(stdin)); execl("./validate", "validate", NULL); close(fd[0]); perror("exec\n"); exit(1); } else { perror("fork\n"); exit(1); } return 0; }

63c648ea5f004bf4898d00e9

2023-01-25T02:27:51.601Z

Help Fix Code

v1

#include <stdio.h> int main() { char phone[11]; int i, j; j = scanf("%s %d", phone, &i); while (j != EOF) { if (i < -1 || i > 9) { printf("ERROR\n"); } else if (i == -1) { printf("%s\n", phone); } else { printf("%c\n", phone[i]);} j = scanf("%d", &i); } return 0; }

63c648ea5f004bf4898d00e9

2023-01-25T19:59:12.149Z

Help Fix Code

v1

#include <stdlib.h> #include <stdio.h> void fib(int *result, int n) { result = malloc(sizeof(int) * n); result[0] = 0; result[1] = 1; int i; for (i = 2; i < n; i++) { result[i] = result[i-2] + result[i-1]; } } int main(int argc, char **argv) { /* do not change this main function */ int count = strtol(argv[1], NULL, 10); int *fib_sequence; fib(&fib_sequence, count); for (int i = 0; i < count; i++) { printf("%d ", fib_sequence[i]); } free(fib_sequence); return 0; }

build a dynamic array containing the first n elements of the Fibonacci sequence

63c648ea5f004bf4898d00e9

2023-01-25T20:02:14.439Z

Help Fix Code

v1

#include <stdlib.h> #include <stdio.h> /* * Define a function void fib(...) below. This function takes parameter n * and generates the first n values in the Fibonacci sequence. Recall that this * sequence is defined as: * 0, 1, 1, 2, 3, 5, ... , fib[n] = fib[n-2] + fib[n-1], ... * The values should be stored in a dynamically-allocated array composed of * exactly the correct number of integers. The values should be returned * through a pointer parameter passed in as the first argument. * * See the main function for an example call to fib. * Pay attention to the expected type of fib's parameters. */ /* Write your solution here */ void fib(int **result, int n) { *result = malloc(sizeof(int) * n); *result[0] = 0; *result[1] = 1; int i; for (i = 2; i < n; i++) { *result[i] = *result[i-2] + *result[i-1]; } } int main(int argc, char **argv) { /* do not change this main function */ int count = strtol(argv[1], NULL, 10); int *fib_sequence; fib(&fib_sequence, count); for (int i = 0; i < count; i++) { printf("%d ", fib_sequence[i]); } free(fib_sequence); return 0; }

build a dynamic array containing the first n elements of the Fibonacci sequence

63c648ea5f004bf4898d00e9

2023-01-25T20:13:42.054Z

Help Fix Code

v1

#include <stdlib.h> #include <stdio.h> /* * Define a function void fib(...) below. This function takes parameter n * and generates the first n values in the Fibonacci sequence. Recall that this * sequence is defined as: * 0, 1, 1, 2, 3, 5, ... , fib[n] = fib[n-2] + fib[n-1], ... * The values should be stored in a dynamically-allocated array composed of * exactly the correct number of integers. The values should be returned * through a pointer parameter passed in as the first argument. * * See the main function for an example call to fib. * Pay attention to the expected type of fib's parameters. */ /* Write your solution here */ void fib(int **result, int n) { *result = malloc(sizeof(int) * n); int *arr = *result; arr[0] = 0; arr[1] = 1; int i; for (i = 2; i < n; i++) { arr[i] = arr[i-2] + arr[i-1]; } } int main(int argc, char **argv) { /* do not change this main function */ int count = strtol(argv[1], NULL, 10); int *fib_sequence; fib(&fib_sequence, count); for (int i = 0; i < count; i++) { printf("%d ", fib_sequence[i]); } free(fib_sequence); return 0; }

build a dynamic array containing the first n elements of the Fibonacci sequence

63c648ea5f004bf4898d00e9

2023-01-25T21:16:33.194Z

Help Fix Code

v1

int **split_array(const int *s, int length) { if (length % 2 == 1) { int *even = malloc(sizeof(int) * (length / 2 + 1)); } else { int *even = malloc(sizeof(int) * (length / 2)); } int *odd = malloc(sizeof(int) * (length / 2)); int i, j; j = 0; for (i = 0; i < length; i += 2) { even[j] = s[i]; j++; } j = 0; for (i = 1; i < length; i += 2) { odd[j] = s[i]; j++; } int arr[2] = {even, odd}; int *ptr = arr; return ptr; }

Return a pointer to an array of two dynamically allocated arrays of ints. The first array contains the elements of the input array s that are at even indices. The second array contains the elements of the input array s that are at odd indices. Do not allocate any more memory than necessary. You are not permitted to include math.h. You can do the math with modulo arithmetic and integer division.

63c648ea5f004bf4898d00e9

2023-01-29T01:04:28.655Z

General Question

v1

how to use scanf to scan a string from index 1 but not 0

63c648ea5f004bf4898d00e9

2023-01-29T01:06:27.129Z

General Question

v1

how to use scanf to scan a string starting from a specific index but not the whole string

63c648ea5f004bf4898d00e9

2023-01-29T01:25:57.871Z

General Question

v1

how to scanf a string from the second char

63c648ea5f004bf4898d00e9

2023-01-29T01:26:39.093Z

General Question

v1

how to scanf a string starting from the second character in string

63c648ea5f004bf4898d00e9

2023-02-09T21:34:44.784Z

Help Write Code

v1

First, allocate space for m `struct pixel *` values, where m is the * height of the image. Each pointer will eventually point to one row of * pixel data. * 2. For each pointer you just allocated, initialize it to point to * heap-allocated space for an entire row of pixel data. * 3. Use the given file and pixel_array_offset to initialize the actual * struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is * consistent with the bitmap file format. * NOTE: We've tested this assumption on the Teaching Lab machines, but * if you're trying to work on your own computer, we strongly recommend * checking this assumption! * 4. Return the address of the first `struct pixel *` you initialized.

63c648ea5f004bf4898d00e9

2023-02-09T21:42:45.132Z

Help Write Code

v1

1. First, allocate space for m `struct pixel *` values, where m is the height of the image. Each pointer will eventually point to one row of pixel data. 2. For each pointer you just allocated, initialize it to point to heap-allocated space for an entire row of pixel data. 3. Use the given file and pixel_array_offset to initialize the actual struct pixel values. Assume that `sizeof(struct pixel) == 3`, which is consistent with the bitmap file format. NOTE: We've tested this assumption on the Teaching Lab machines, but if you're trying to work on your own computer, we strongly recommend checking this assumption! 4. Return the address of the first `struct pixel *` you initialized.