c - Segmentation fault 11 on boolean method -

i'm trying use method return 1 true , 0 false, gives me "segmentation fault: 11" if returns false. i've been janking brain trying figure out i'm messing can't seem find anything.

here's code.

first call function

int delete_number; printf("select number remove list?\n"); scanf("%i", &delete_number);   if(remove_num(delete_number)) {     printf("deleted %i ", delete_number); } else {     printf("number %i not found in list", delete_number); } 

now function itself

int remove_num(int data)  {     int result = 0;     node *curr_ptr;     node *prev_ptr;     node *temp_ptr;      if(queuer.first != null)     {         if(queuer.first->data == data)         {             temp_ptr = queuer.first;             queuer.first = queuer.first->next;              if(queuer.first == null)             {                 queuer.last = null;             }              free(temp_ptr);             result = 1;         }         else         {             prev_ptr = queuer.first;             curr_ptr = queuer.first->next;              while(curr_ptr->data != data && curr_ptr != null)             {                 prev_ptr = curr_ptr;                 curr_ptr = prev_ptr->next;             }              if(curr_ptr != null)             {                 temp_ptr = curr_ptr;                 prev_ptr->next = temp_ptr->next;                  free(temp_ptr);                 result = 1;             }         }     }      return result; } 

i may have misunderstood seg. fault thought occurs because of how run through list while-loop. said, when user inputs number existing in list, works fine. when number inputted not in list seg.fault occurs.

you need change:

        while(curr_ptr->data != data && curr_ptr != null) 

to:

        while(curr_ptr != null && curr_ptr->data != data) 

the tests in && executed left-to-right. mustn't dereference curr_ptr until you've verified it's valid.