Why am i getting segmentation fault in deleting node? - c

Question

node * del(node * start,int loc)
{
int l=len(start);
if(loc<1 || loc>l)
{
printf("Deletion not possible. \n");
}
else
{
if(loc==1)
{
node *p;
p=start;
start=start->next;
free(p);
}
else
{
node *p,*q;
p=start;
for(int i=1;i<=loc-1;i++)//check this one.
{
q=p;
p=p->next;
}
q->next=p->next;
free(p);
}
printf("Deletion completed!\n");
}
return start;
}
This is the function and I am calling it from main() as:
case 5:
printf("Enter the node you want to delete. \n");
scanf("%d",temp);
start=del(start,temp);
break;
While deleting any node I am getting segmentation fault!I am stuck at this .
Can anyone help?
here is the full program:-
#include<stdio.h>
#include<stdbool.h>
#include<stdlib.h>
struct Node
{
int data;
struct Node * next;
};
typedef struct Node node;
int len(node * start)
{
if(start==NULL)
return 0;
int c=1;
while(start!=NULL)
{
start=start->next;
c++;
}
return c;
}
node * insert(node* start,int loc,int d)
{
int l=len(start);
node * p=start;
node * temp=(node*)malloc(sizeof(node));
if(loc<1 || loc>l+1)
{
printf("Insertion not posible.!\n");
return start;
}
if(l==0 || loc==1)
{
temp->next=start;
start=temp;
temp->data=d;
printf("Insertion completed.\n");
}
else
{
for(int i=1;i<=loc-2;i++)
p=p->next;
temp->next=p->next;
p->next=temp;
temp->data=d;
printf("Insertion completed. \n");
}
return start;
}
void show(node *start)
{
int l=len(start);
if(l==0)
{
printf("Nothing to print. \n");
}
else
{
for(int i=1;i<l-1;i++)
{
printf(" %d -> ",start->data);
start=start->next;
}
printf(" %d \n",start->data);
}
}
node * destroy(node * start)
{
node * p=start;
while(start!=NULL)
{
start=start->next;
free(p);
p=start;
}
printf("Destroy of linked list completed! .\n");
return NULL;
}
node * del(node * start,int loc)
{
int l=len(start);
if(loc<1 || loc>l)
{
printf("Deletion not possible. \n");
}
else
{
if(loc==1)
{
node *p;
p=start;
start=start->next;
free(p);
}
else
{
node *p,*q;
p=start;
for(int i=1;i<=loc-1;i++)//check this one.
{
q=p;
p=p->next;
}
q->next=p->next;
free(p);
}
printf("Deletion completed!\n");
}
return start;
}
int main()
{
node * start=NULL;
int ch,temp,d;
ch=temp=d=0;
while(ch != -1)
{
switch(ch)
{
case 0:
printf("Enter 0 to show menu.\n");
printf("Enter 1 to create linked list.\n");
printf("Enter 2 to destroy linked list.\n");
printf("Enter 3 to get the length of likned list.\n");
printf("Enter 4 to insert element in the linked list.\n");
printf("Enter 5 to delete element from the linked list.\n");
printf("Enter 6 to view the linked list.\n");
printf("Enter 7 to reverse a linked list.\n");
break;
case 1:
printf("Enter the size of link list to begin with.\n");
scanf("%d",&temp);
for(int i=1;i<=temp;i++)
{
printf("Enter the data to bes inserted to node %d .\n",i);
scanf("%d",&d);
start=insert(start,i,d);
}
break;
case 2:
start=destroy(start);
break;
case 3:
printf("Size of linked list is: %d \n",len(start));
break;
case 4:
printf("Enter the location where you want to insert the data.\n");
scanf("%d",&temp);
printf("Enter the data to be intered.\n");
scanf("%d",&d);
start=insert(start,temp,d);
break;
case 5:
printf("Enter the node you want to delete. \n");
scanf("%d",temp);
start=del(start,temp);
break;
case 6:
show(start);
break;
default:
ch=0;
break;
}
printf("\nEnter your choice? \n");
scanf("%d",&ch);
}
destroy(start);
}

Answer 1

Change:
case 5:
printf("Enter the node you want to delete. \n");
scanf("%d",temp);
start=del(start,temp);
break;
line scanf("%d",temp); to scanf("%d",&temp);