Need help Debugging (ADT)
Hello, I been trying to debug my program for hours, but there still one small bug left that I need help. Please anyone can give me some advice/tip, it would be very much appreciated.
I used gdb to debug my program, and it tell that my program is Segmentation Fault at line 207.
when I run gdb with my program, here what I get:
Code:
(gdb) run in out
Starting program: /afs/cats.ucsc.edu/users/m/ltrinh1/private/cs101/pa5/FindComponents in out
Program received signal SIGSEGV, Segmentation fault.
0x0000000000401dc1 in insertBeforeFirst (L=0x604630, data=1) at List.c:207
207 L->head->prev= temp;
Here's my Code.
Code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include "List.h"
typedef struct Node{
int data;
struct Node* next;
struct Node* prev;
} Node;
typedef Node* NodeRef;
typedef struct List{
NodeRef head;
NodeRef tail;
NodeRef curr;
int length;
} List;
NodeRef newNode(int node_data){
NodeRef N = malloc(sizeof(Node));
N->data= node_data;
N->next= NULL;
return (N);
}
void freeNode(NodeRef* pN){
if(pN !=NULL && *pN!=NULL){
free(*pN);
*pN= NULL;
}
}
ListRef newList(void){
ListRef L;
L = malloc(sizeof(List));
L->head = L->tail = NULL;
L-> length =0;
return(L);
}
void freeList(ListRef* pL){
if(pL== NULL || *pL==NULL){ return;}
makeEmpty(*pL);
free(pL);
free(*pL);
*pL= NULL;
}
int isEmpty(ListRef L){
if(L==NULL){
printf("Error: calling is isEmpty() on NULL ListRef\n");
exit(1);
}
if(L->length==0){
return 1;
}
return (L->length==0);
}
int offEnd(ListRef L){
if(L->curr== NULL){ return 1; }
if(getLength(L)==0){ return 1;}
return 0;
}
int atFirst(ListRef L){
if(isEmpty(L)){ return 0; }
if(L->head== L->curr){ return 1; }
return 0;
}
int atLast(ListRef L){
if(isEmpty(L)){ return 0; }
if(L->tail == L->curr){ return 1; }
return 0;
}
int getFirst(ListRef L){
if(L ==NULL){
printf("Called getFirst on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){
printf("Called getFirst on an empty list\n");
exit(1);
}
return(L->head->data);
}
int getLast(ListRef L){
if(L== NULL){
printf("Error: Called getLast on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){
printf("Error: Called getLast on an empty list\n");
exit(1);
}
return(L->tail->data);
}
int getCurrent(ListRef L){
if(L==NULL){
printf("Error: Called getCurrent on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) && offEnd(L)){
printf("Error: Called getCurrent on an empty list\n");
exit(1);
}
return(L->curr->data);
}
int getLength(ListRef L){
if(L== NULL){
printf("Error: Called getLength on NULL ListRef\n");
exit(1);
}
return(L->length);
}
int equals(ListRef L, ListRef K){
int flag = 1;
Node* tempOne= NULL;
Node* tempTwo= NULL;
if(L== NULL || K== NULL){
printf("Error: calling equals() on NULL ListRef\n");
exit(1);
}
if(L->length != K->length){return 0; }
tempOne= L->head;
tempTwo= K->head;
while(flag && tempOne != NULL){
flag = (tempOne->data == tempTwo->data);
tempOne = tempOne->next;
tempTwo = tempTwo->next;
}
return flag;
}
void makeEmpty(ListRef L){
while(!isEmpty(L)){
deleteFirst(L);
}
}
void moveFirst(ListRef L){
if(L== NULL){
printf("Error: moveFirst() called on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) && offEnd(L)){
printf("Error: List is empty. (moveFirst)\n");
exit(1);
}
L->curr = L->head;
}
void moveLast(ListRef L){
if(L== NULL){
printf("Error: moveLast() called on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)&& offEnd(L)){
printf("Error: List is empty. (moveLast)\n");
exit(1);
}
L->curr= L->tail;
}
void movePrev(ListRef L){
if(L== NULL){
printf("Error: called movePrev() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) && offEnd(L)){
printf("Error: List is empty. (movePrev)\n");
exit(1);
}
L->curr= L->curr->prev;
}
void moveNext(ListRef L){
if(L== NULL){
printf("Error: called moveNext() on NULL ListRef \n");
exit(1);
}
if(isEmpty(L) && offEnd(L)){
printf("Error: List is empty. (moveNext)");
exit(1);
}
L->curr= L->curr->next;
}
void insertBeforeFirst(ListRef L, int data){
NodeRef temp= newNode(data);
if(L== NULL){
printf("Queue Error: called insertBeforeFirst() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){ L->head= L->tail= temp; }
else{
temp->next = L->head;
L->head->prev= temp;
L->head= temp;
}
L->length++;
}
void insertAfterLast(ListRef L, int data){
NodeRef temp = newNode(data);
if(L== NULL){
printf("Error: called insertAfterLast() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){ L->head= L->tail= temp; }
else{
temp->prev= L->tail;
L->tail->next= temp;
L->tail= temp;
}
L->length++;
}
void insertBeforeCurrent(ListRef L, int data){
if(L== NULL){
printf("Error: calling insertBeforeCurrent() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) || offEnd(L)){
printf("Error: List is empty or Current node is NULL.\n");
exit(1);
}
if(atFirst(L)){
insertBeforeFirst(L,data);
}
else{
NodeRef temp = newNode(data);
temp->prev = L->curr->prev;
temp->next = L->curr;
(L->curr->prev)->next= temp;
L->curr->prev = temp;
L->length++;
freeNode( &temp);
}
}
void insertAfterCurrent(ListRef L, int data){
if(L== NULL){
printf("Error: called insertAfterCurrent() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) || offEnd(L)){
printf("Error: List is empty/Current node is NULL.(insertAfterCurrent)\n");
}
if(atLast(L)){
insertAfterLast(L,data);
}
else{
NodeRef temp = newNode(data);
temp->next= L->curr->next;
temp->prev= L->curr;
(L->curr->next)->prev= temp;
L->curr->next= temp;
L->length++;
}
}
void deleteFirst(ListRef L){
NodeRef temp= NULL;
if(L== NULL){
printf("Error: called deleteFirst() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){
printf("Error: deleteFirst called on empty list.");
exit(1);
}
temp= L->head;
if(L->length>1){
(L->head->next)->prev= NULL;
L->head= L->head->next;
L->length--;
}
else{
L->head= L->tail= NULL;
L->length= 0;
}
freeNode(&temp);
free(temp);
}
void deleteLast(ListRef L){
NodeRef temp = NULL;
if(L== NULL){
printf("Error: called deleteLast() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){
printf("Error: deleteLast called on empty list.");
exit(1);
}
temp= L->tail;
if(L->length>1){
(L->tail->prev)->next= NULL;
L->tail= L->tail->prev;
L->length--;
}
else{
L->head= L->tail= NULL;
L->length=0;
}
freeNode(&temp);
}
void deleteCurrent(ListRef L){
if(L== NULL){
printf("Error: deleteCurrent() called on NULL ListRef\n");
exit(1);
}
if(isEmpty(L) && offEnd(L)){
printf("Error: deleteCurrent called on empty list.");
exit(1);
}
if(atFirst(L)){
deleteFirst(L);
}
else if(atLast(L)){
deleteLast(L);
}
else if(L->length>1){
NodeRef temp = NULL;
temp= L->curr;
(L->curr->prev)->next= L->curr->next;
(L->curr->next)->prev= L->curr->prev;
L->curr->next= NULL;
L->curr->prev= NULL;
L->length--;
freeNode(&temp);
}
}
void printList(FILE* out, ListRef L){
if(out == NULL){
printf("Unable to open file for writing\n");
exit(1);
}
if(L == NULL){
printf("Error: Unable to write List to file\n");
exit(1);
}
NodeRef temp;
for(temp= L->head; temp!=NULL; temp=temp->next){
fprintf(out, "%d ", temp->data);
}
fprintf(out,"\n");
}
ListRef copyList(ListRef L){
ListRef temp = newList();
NodeRef tempNode= L->head;
while( tempNode != NULL){
insertAfterLast(temp, tempNode->data);
tempNode= tempNode->next;
}
return temp;
}
void shuffleLists(ListRef L, ListRef P){
moveFirst(P);
int position, i, j;
moveLast(L);
while(!offEnd(P)){
position = getCurrent(P);
for(i =1; i< position; i++){
moveNext(L);
}
insertAfterCurrent(L,getFirst(L));
deleteFirst(L);
for(j =1; j< position; j++){
movePrev(L);
}
moveNext(P);
}
}
void printerList(ListRef L){
NodeRef temp= NULL;
if(L == NULL){
printf("Error: Fail.\n");
exit(1);
}
for(temp= L->head; temp!= NULL; temp=temp->next){
printf("%d ", temp->data);
}
printf("\n");
}
Line 207 is
Code:
L->head->prev= temp;
From
Code:
void insertBeforeFirst(ListRef L, int data){
NodeRef temp= newNode(data);
if(L== NULL){
printf("Queue Error: called insertBeforeFirst() on NULL ListRef\n");
exit(1);
}
if(isEmpty(L)){ L->head= L->tail= temp; }
else{
temp->next = L->head;
L->head->prev= temp;
L->head= temp;
}
L->length++;
}
I don't see what's wrong with line 207, I just did the opposite of insertAfterLast
