You should be able to enter any movie title and genre into this program as long as they are smaller then 30 characters. Then insert a rating between 1-5. The insert function takes those three inputs and stores them into a doubly linked list. After Two entries into this list the program creates an unexpected breakpoint on this line newBlock = (movieInfo*)malloc(sizeof(movieInfo)); The problems is in the insert function.
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
typedef struct movieInfo {
char* title;
char* genre;
int rating;
struct movieInfo* prev;
struct movieInfo* next;
}movieInfo;
//prototypes
int getNum(void);
movieInfo insert(char* title, char *genre,int rating, movieInfo** head, movienfo** tail);
void showList(movieInfo* head);
void eliminateEndOfLine(char* buffer);
void eliminateEndOfLine(char* buffer);
#define kWhileLoopCounter 1
#define kBuffer 30
int main() {
char title[kBuffer];
char genre[kBuffer];
int rating = 0;
movieInfo* head = NULL;
movieInfo* tail = NULL;
movieInfo* node = NULL;
while (kWhileLoopCounter) {
printf("Please enter a title or exit the loop by entering ""."" and enter \n");
fgets(title, kBuffer, stdin);
if (strcmp(title, ".\n") == 0) {
break;
}
eliminateEndOfLine(title);
printf("Please enter a genre or exit the loop by entering ""."" and enter \n");
fgets(genre, kBuffer, stdin);
if (strcmp(genre, ".\n") == 0) {
break;
}
eliminateEndOfLine(genre);
for (;;) { //jut to check and make sure the user does not enter a value greater then one
printf("Please enter a rating between 1-5\n");
rating = getNum();
if (rating < 1) {
printf("The number you have entered in less then 1,\n\n");
}
else if (rating > 5) {
printf("The number you have entered is greater than 5\n\n");
}
else {
insert(title, genre, rating, &head, &tail);
break;
}
}
}
showList(head);
freeAll(head);
return 0;}
This function seems to be the problem!!!
movieInfo insert(char title[],char genre[],int rating, movieInfo** head, movieInfo** tail) {
movieInfo* newBlock = NULL;
movieInfo* beforeElement = NULL;
movieInfo* afterElement = NULL;
newBlock = (movieInfo*)malloc(sizeof(movieInfo));
newBlock->title = (char*)malloc((strlen(title) + 1));
newBlock->genre = (char*)malloc((strlen(genre) + 1));
/*newBlock->rating = (int*)malloc(1);*/
if (newBlock == NULL) {
printf("No memory was allocated \n");
return **head;
}
strncpy(newBlock->title, title,30);
strncpy(newBlock->genre, genre,30);
newBlock->prev = newBlock->next = NULL;
if (*head == NULL) {
*head = *tail = newBlock;
return**head;
}
else if (strcmp((*head)->title, title) >= 0) {
newBlock->next = *head;
(*head)->prev = newBlock;
*head = newBlock;
}
else {
beforeElement = *head;
afterElement = (*head)->next;
while (afterElement != NULL) {
if (strcmp(afterElement->title, title) >= 0) {
break;
}
beforeElement = afterElement;
afterElement = afterElement->next;
}
newBlock->prev = beforeElement;
newBlock->next = afterElement;
beforeElement->next = newBlock;
if (afterElement == NULL)
{
*tail = newBlock;
}
else
{
afterElement->prev = newBlock;
}
}
return **head;
}
This contains the smaller functions.
void showList(movieInfo* head)
{
movieInfo* item = NULL;
item = head;
char titleHeader[] = "Title";
char genreHeader[] = "Genre";
char ratingHeader[] = "Rating";
printf("\n\n%-30s %-30s %-30s\n",titleHeader,genreHeader,ratingHeader);
while (item != NULL)
{
printf("%-30s %-30s %-30d\n", item->title,item->genre, item->rating);
item = item->next;
}
}
int getNum(void)
{/* the array is 121 bytes in size; we'll see in a later lecture how we can improve this code */
char record[121] = { 0 }; /* record stores the string */
int number = 0;
/* NOTE to student: indent and brace this function consistent with your others */
/* use fgets() to get a string from the keyboard */
fgets(record, 121, stdin);
/* extract the number from the string; sscanf() returns a number
* corresponding with the number of items it found in the string */
if (sscanf(record, "%d", &number) != 1)
{
/* if the user did not enter a number recognizable by
* the system, set number to -1 */
number = -1;
}
return number;
}
void eliminateEndOfLine(char* buffer)
{
char* target = strchr(buffer, '\n');
if (target != NULL)
{
*target = '\0';
}
}
void freeAll(movieInfo* head)//This function frees the head
{
movieInfo* curr = NULL, * next = NULL;
curr = head;
// traverse the list, being careful to not access freed blocks
while (curr != NULL)
{
// keep a pointer to the next block so we can go there after it's freed
next = curr->next;
free(curr);
curr = next;
}
}
