segmentation fault(core dump)

i was trying to run a c program where i was trying to implement the stack data structure using linked list. my linux version is ubuntu 10.04 and while running i get the error segmentation fault(core dump) after which the program doesnot run any more on the terminal. i am giving the coding as well.]

Code:

#include<stdio.h>
#include<stdlib.h>

struct stack
{
int data;
struct stack *link;
int top;
};

typedef struct stack stack;

void push(struct stack *,int item);
int pop(struct stack *);
void display(struct stack *);

int main()
{
struct stack s;
int noofelements_push,elements_push;
int noofelements_pop;
int i,j;

printf("\n Enter no. of elements to push:");
scanf("%d",&noofelements_push);
for(i=0;i<noofelements_push;i++)
{
printf("\n Enter the elements:");
scanf("%d",&elements_push);
push(&s,elements_push);
fflush(stdin);
}

display(&s);

printf("\n Enter no. of elements to pop:");
scanf("%d",&noofelements_pop);
for(i=0;i<noofelements_pop;i++)
{
j=pop(&s);
printf("\n the poped element is:%d",j);
}

display(&s);

return (0);
}

void push(struct stack *s,int item)
{
stack *newnode,*temp;
newnode=(stack *)malloc(sizeof(stack));
newnode->data=item;
newnode->link=NULL;
if(s==NULL)
{
s=newnode;
}
else
{
temp=s;
while(temp->link!=NULL)
{
temp=temp->link;
}
temp->link=newnode;
}
}

int pop(struct stack *s)
{
stack *temp,*prev;
int i;
temp=s;
while(temp->link!=NULL)
{
prev=temp;
temp=temp->link;
}
i=temp->data;
free(temp);
prev->link=NULL;
return(i);
}

void display(struct stack *s)
{
while(s!=NULL)
{
printf("\n %d",s->data);
s=s->link;
}
}

Your #1 problem is you need to adopt a conventional coding style -- one with indents. Something like this:

Code:

#include<stdio.h>
#include<stdlib.h>

struct stack
{
        int data;
        struct stack *link;
        int top;
};

typedef struct stack stack;

void push(struct stack *,int item);
int pop(struct stack *);
void display(struct stack *);

int main()
{
        struct stack s;
        int noofelements_push,elements_push;
        int noofelements_pop;
        int i,j;

        printf("\n Enter no. of elements to push:");
        scanf("%d",&noofelements_push);
        for(i=0;i<noofelements_push;i++)
        {
                printf("\n Enter the elements:");
                scanf("%d",&elements_push);
                push(&s,elements_push);
                fflush(stdin);// BIG NO NO here!!
        }

        display(&s);

        printf("\n Enter no. of elements to pop:");
        scanf("%d",&noofelements_pop);
        for(i=0;i<noofelements_pop;i++)
        {
                j=pop(&s);
                printf("\n the poped element is:%d",j);
        }

        display(&s);

        return (0);
}

void push(struct stack *s,int item)
{
        stack *newnode,*temp;
        newnode=(stack *)malloc(sizeof(stack));
        newnode->data=item;
        newnode->link=NULL;
        if(s==NULL)
        {
                s=newnode;
        }
        else
        {
                temp=s;
                while(temp->link!=NULL)
                {
                        temp=temp->link;
                }
                temp->link=newnode;
        }
}

int pop(struct stack *s)
{
        stack *temp,*prev;
        int i;
        temp=s;
        while(temp->link!=NULL)
        {
                prev=temp;
                temp=temp->link;
        }
        i=temp->data;
        free(temp);
        prev->link=NULL;
        return(i);
}

void display(struct stack *s)
{
        while(s!=NULL)
        {
                printf("\n %d",s->data);
                s=s->link;
        }
}

There is a rather rash thing you've done. Take that out and try again. If you want to flush stdin, you READ IT. Something like while (getchar() != '\n'); will work for you.

Maybe it's the lack of indentation?
Indent style - Wikipedia, the free encyclopedia

Well it isn't, but the lack of indentation is a big turn-off for anyone wanting to look at the code.

Is it as badly formatted in your source code editor?

prev is uninitialized in pop, and you're dereferencing it.