pointer question C

[pandaemonia]

I have the code

Bool enqueue(Queue *AQueue, int processId, int arrivalTime,
int serviceTime, int remainingTime) {
Node *head;
head = AQueue->head;
Node *tail;
tail = AQueue->tail;
Node *tempnode;
tempnode = (Node*)malloc(sizeof(Node));

tempnode->processId = processId;
tempnode->arrivalTime = arrivalTime;
tempnode->serviceTime = serviceTime;
tempnode->remainingTime = remainingTime;
tempnode->next = NULL;

if (tail == NULL){
tail = tempnode;
head = tempnode;
} else {
(tail)->next = tempnode;
tail = tempnode;
}
return TRUE;
}.

The .h file is as follows:

typedef struct node{
int processId;
int arrivalTime;
int serviceTime;
int remainingTime;
struct node *next; // points to the next node
} Node;


typedef struct queue{
Node *head;
Node *tail;
} Queue;

It's not actually adding anything to the queue. Why?

[veda87]

tempnode = (Node*)malloc(sizeof(Node));

you have allocated memory for sizeof(Node) but Node is a pointer ... so it allocates only 4 bytes ...so it won,t work.... you have have allocate for entire struct node...

tempnode = (Node*)malloc(sizeof(struct node));

this will do ......hope you understand....

[movieman]

you have allocated memory for sizeof(Node) but Node is a pointer ...

Node is a structure, so that should be fine.

The real problem is that the code only updates local variables, so the results of the update will disappear as soon as you return from the function call.

You need to update AQueue->head and AQueue-tail, not local copies of them.