Why is this simple linked list program giving segmentation fault?

Question

I am simply trying to create a linked list of characters. Here's the code:

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

struct node{
    char data;
    struct node *next;
};

void push(struct node** head,char ndata)
{
    struct node* temp=(struct node*)malloc(sizeof(node));
    temp->data=ndata;
    temp->next=(*head);
    *head=temp;
}

void display(struct node* head)
{
    struct node* temp=head;

    while(temp)
    {
        printf("%c ",temp->data);
        temp=temp->next;
    }   
}

int main()
{
    struct node* head;
    int a=1;
    push(&head,'a');
    push(&head,'b');
    push(&head,'c');
    push(&head,'b');
    push(&head,'a');

    display(head);  
    getch();
    return 0;
}

I am using push() function which inserts the values at head. And then using display() method to display the values in the list. When I execute the program, it says "program10.exe has stopped working". I don't understand what the problem is. Can anyone help?

I am using Dev-CPP compiler. It automatically "attaches" typedef. — Siddharth
– Siddharth, Commented Feb 1, 2015 at 15:21

MByD · Accepted Answer · 2015-02-01 15:14:27Z

3

You didn't initialize head so it's not null but has a garbage value, so it doesn't stop the loop in the display function, and tries to dereference garbage there.

This:

struct node* head;

Should be:

struct node* head = NULL;

answered Feb 1, 2015 at 15:14

MByD

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1 Comment

Siddharth Over a year ago

Damn. How did I miss that? Thanks mate.

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