Malloc() & Free()

[fajewel]

struct node{

char *data;
struct node *link;
};

struct node first;

int main()
{
char *ptr;
ptr=malloc(sizeof(char)*100);
first=malloc(sizeof(struct node));
first->data=ptr;
first->link='\0';
free(first);
free(ptr);
return 0;
}


Experts, Please say what is the wrong with this code ? Am I try to free the memory address which is already free?

Please give me the explanation. If it is possible provide me the pictorial explanation.

Thank you.

[Disch]

You're treating 'first' like it's a pointer, but it's not a pointer.

//struct node first;   <---  not a pointer
struct node *first;  // <--- a pointer 

Other than that, I don't see anything wrong. first->link='\0'; is a little weird, but shouldn't be a problem.

[fajewel]

Thank you for replay. Sorry for the typing mistake... Original code like below

struct node{

char *data;
struct node *link;
};

struct node *first;

int main()
{
char *ptr;
ptr=malloc(sizeof(char)*100);
first=malloc(sizeof(struct node));
first->data=ptr;
first->link='\0';
free(first);
free(ptr);
return 0;
}

[This code are making run time problem in my linux os. Trying to free the unallocated memory]

[helios]

Works for me.