Issue with free() for linked list implementation

[Namespace via Digitalmars-d-learn]

On Friday, 3 April 2015 at 22:02:13 UTC, Kitt wrote:
> Hello. I’m trying to write my own version of a list that 
> doesn’t rely on the garbage collector. I’m working on a very 
> bare bones implementation using malloc and free, but I’m 
> running into an exception when I attempt to call free. Here is 
> a very minimal code sample to illustrate the issue:
>
> // Some constant values we can use
> static const int two = 2, ten = 10;
>
> // Get memory for two new nodes
> Node* head = cast(Node*)malloc(two.sizeof);
> Node* node1 = cast(Node*)malloc(ten.sizeof);
>
> // Initialize the nodes
> node1.value = ten;
> node1.next = null;
> head.value = two;	
> head.next = node1;
>
> // Attempt to free the head node
> Node* temp = head.next;
> head.next = null;
> free(head); // Exception right here
> head = temp;
>
> Note, if I comment out the line ‘head.next = node1’, this code 
> works. Does anyone know what I’m doing wrong with my manual 
> memory management?

Why did you allocate only 2 / 10 bytes and not Node.sizeof bytes?
Since your Node struct has at least one pointer (nexT) and a 
value (I assume of type int) you must allocate at least 8 bytes 
for one Node. I'm sure that is at least one of your problems.