Modify project 10 by adding and modifying the following function:

Add a delete_from_list function in dogs.c that deletes a dog from the list. The function should delete by the dogs patient number. The dogs patient number will be entered by the user. The function should have the following prototype: struct dog* delete_from_list(struct dog *dogs); You will also need to add the function prototype to the header file; modify the main function in records.c to add d for delete option in the menu and it calls the delete function when the d option is selected.

CODE PROVIDED BELOW:

#include #include #include #include

#define NAME_LEN 30

struct dog{ int number; char dog_name[NAME_LEN+1]; char owner_last_name[NAME_LEN+1]; char breed[NAME_LEN+1]; struct dog *next; };

/*function prototypes*/ struct dog *append(struct dog *list); void search(struct dog *list); void print(struct dog *list); void clear(struct dog *list); int read_line(char str[], int n);

/********************************************************** * main: Prompts the user to enter an operation code, * * then calls a function to perform the requested * * action. Repeats until the user enters the * * command 'q'. Prints an error message if the user * * enters an illegal code. * **********************************************************/ int main(void) { char code;

struct dog *dog_list = NULL; printf("Operation Code: a for appending to the list, s for finding a dog" ", p for printing the list; q for quit. "); for (;;) { printf("Enter operation code: "); scanf(" %c", &code); while (getchar() != ' ') /* skips to end of line */ ; switch (code) { case 'a': dog_list = append(dog_list); break; case 's': search(dog_list); break; case 'p': print(dog_list); break; case 'q': clear(dog_list); return 0; default: printf("Illegal code "); } printf(" "); } }

/************************************************************ * append: Prompts the user for informaiton about a dog and * * then append the dog structure to the end of the list. * * Prints an error message and returns prematurely if the * * dog already exists by its patient number or memory * * could not be allocated for the dog structure. * * *********************************************************/

struct dog *append(struct dog *list){ struct dog *cur, *new_node;

new_node = malloc(sizeof(struct dog)); if (new_node == NULL) { printf("Database is full; can't add more dogs. "); return list; }

printf("Enter dog's patient number: "); scanf("%d", &new_node->number);

for (cur = list;cur != NULL;cur = cur->next) if (cur != NULL && new_node->number == cur->number) { printf("Patient already exists. "); free(new_node); return list; }

printf("Enter dog's name: "); read_line(new_node->dog_name, NAME_LEN); printf("Enter dog's breed: "); read_line(new_node->breed, NAME_LEN); printf("Enter owner's last name: "); read_line(new_node->owner_last_name, NAME_LEN); new_node->next = NULL;

if(list == NULL) { list = new_node; return list; } else{ for(cur = list; cur->next!= NULL; cur = cur->next); cur->next = new_node; return list; }

}

/*********************************************************** * search: Prompts the user to enter a dog's name, then * * looks up dog(s) by name in the list. Prints the all the * * informaiton of the dogs with the name if found. * * Otherwise, prints a message. * * ********************************************************/

void search (struct dog *list) { char search_name[NAME_LEN+1]; struct dog *p; int found =0; printf("Enter dog's name: "); read_line(search_name, NAME_LEN);

for(p=list; p != NULL; p = p->next) { if(strcmp(search_name, p->dog_name)==0){ found = 1; printf("%d\t", p->number); printf("%s\t", p->dog_name); printf("%s\t", p->breed); printf("%s ", p->owner_last_name); } } if(!found) printf("dog not found. ");

}

/************************************************************ * print: Prints a listing of all dogs in the list, showing * * the dog's patient number, name, breed, and owner's last * * name. * * *********************************************************/

void print(struct dog *list){

struct dog *p;

printf("Dog Number\tDog Name\t" "Dog Breed\tOwner Last Name "); for (p = list; p != NULL; p = p->next) printf("%d\t\t%s\t\t%s\t\t%s ", p->number, p->dog_name,p->breed, p->owner_last_name);

} /*************************************************************** * clear: Clears the entire linked list. It begins at the head * * of the list and frees memory allocated for each node of the * * linked list. * * ************************************************************/

void clear(struct dog *list) { struct dog *p;

while(list!=NULL) { p = list; list = list->next; if(p!=NULL) free(p); }

}

/*************************************************************** * read_line: Skips leading white-space characers, then reads * * the remainder of the input line and stores it in str. * * Truncate the line if its length exceeds n. Returns the * * number of characters stored. * * ************************************************************/

int read_line(char str[], int n) { int ch, i = 0;

while (isspace(ch = getchar())) ; str[i++] = ch; while ((ch = getchar()) != ' ') { if (i < n) str[i++] = ch; } str[i] = '\0'; return i; }