如何释放链表？

Question

I have created a linked list in a function and throughout the rest of the program I am accessing the list using a pointer. Now how would I free this linked list at the end of my program? Do I plainly use free(CircuitData) or do I have to run through the list freeing each node? Writing this I'm thinking freeing each node is the obvious answer...

On a side note I'd also like to ask how to find out whether all memory allocated during a program is freed properly?

 ListNodeType *CircuitData;
 CircuitData = NULL;
 ReadFile(&CircuitData, &numEl, &numNodes);


void ReadFile(ListNodeType **CircuitData, int *numEl, int *numNodes){

    ListNodeType *newPtr, *tempPtr;
    newPtr = malloc(sizeof(ListNodeType));
    *CircuitData = newPtr;
    newPtr->nextPtr = NULL;

    //MORE CODE

Answer 1

I would think of something like this:

struct node
{
    int data;
    node* next;
} *head;

void deleteAllNodes(node* start)
{
    while (start != NULL)
    { 
        node* temp = start; 
        start = start -> next;
        free(temp);
    }
}

Answer 2

I think you can do something like this :

void freeFunction(ListNodeType *CircuitData)
{
    void *victim;

    while (CircuitData)
    {
        victim = CircuitData;
        CircuitData = CircuitData->next;
        free(victim);
    }
}

Answer 3

For every malloc you will need a free otherwise you will leak memory. One possible way to analyze your program to see if you don't have memory leaks is to use Valgrind .

Answer 4

For your first question, yes, you should walk the list and free each node.

The second question is a bit harder to answer. If you have an object in memory, but no way to access it, that's a memory leak.

There are tools you can use to analyze your memory pool. Check out valgrind:

http://valgrind.org/