Issue with free() for linked list implementation

[Kitt via Digitalmars-d-learn]

On Friday, 3 April 2015 at 22:06:06 UTC, Namespace wrote:
> 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.

Wow, I can't even begin to explain how red my cheeks are right 
now. You're completely right; I have no idea what my head was 
thinking. Sure enough, call malloc with the correct type, and the 
error goes away =P

Thanks for the help =) I guess I've been in C# land at work for 
way too long now, my low level C skills are evaporating!