program compiles and runs but after sometime it stops working in cpp ,using typedef keyword

Question

i am using this code but it is not running. it is not running in Dev C++. it runs then blows up.

#include <iostream>
using namespace std;
struct Node
{
    struct Node* left;
    int data;
    struct Node* right;
};
typedef struct Node *node;
int main()
{
    node n;
    n->data = 4;
    cout << n->data << endl;
    return 0;
}

i got that, actually we need to provide memory for n then it could contain data field and others too. — Amit, Oct 03 '17 at 17:22
idid that using malloc ,well new is also fine. thanks guys,. — Amit, Oct 03 '17 at 17:24

P.An · Accepted Answer · 2017-10-03T14:38:09.880

0

You need to allocate memory for n before using it, something like:

node n = new Node;

edited Oct 03 '17 at 14:38

answered Oct 03 '17 at 14:26

P.An

355
1
9

Change allocate to initialise – Richard Critten Oct 03 '17 at 14:31
@StoryTeller If you exclude typedef, `n` would be a pointer to a structure of type Node, which is not allocated - you get a segmentation violation running it. Author should do something like: `node n = new Node;` – P.An Oct 03 '17 at 14:36

ProXicT · Answer 2 · 2017-10-03T14:59:23.797

Clearly the n variable is just a pointer which points to who knows where. You need to assign it some memory address where it can read the data from or write to.
This should do the trick:

node n = new Node;

The typedef struct Node *node; might be a little confusing for you.
You can write:

Node* n = new Node;

And get rid off the typedef which is much more clear that the n is just a pointer and thus you need to assign it some address where it points to.

program compiles and runs but after sometime it stops working in cpp ,using typedef keyword

2 Answers2