segmentation fault linked list

Question

I see some similar topic but they didn't help me. I have make linked list, and a function to insert elements. ``` struct node{ int data; struct node* next; } node; struct node* head; void insert(struct node* head,int x); int main(){ struct node* head = (struct node*) malloc(sizeof(struct node)); int x; while(1){ printf("Please enter number
"); scanf("%i", &x); insert(head,x); print(head); // function that works } return 0; } void insert(struct node* head,int x){ struct node* temp = malloc(sizeof(struct node)); temp->data = x; temp->next = NULL; if(head->next != NULL) temp->next = head; head = temp; free(temp); } ``` GDB says that I'm getting segmentation fault on the line with the if construction: ``` if(head->next != NULL) temp->next = head; ``` Where is my mistake ?

Accepted Answer

Yes ofcourse it will give segmentation fault. In `if` condition you are accessing `head->next`. `head` is just pointer of type `struct node`. First allocate the memory space and then access the field. Right now you are accessing `(head->next)` which is some inappropriate address in the memory and kernel gives "segmentation fault" to the process. For e.g do `struct node* head = malloc(sizeof(struct node));` and then one can access `head->next`.

segmentation fault linked list

Solution

Problem