Question

What is wrong with addAtBegin? The list seems to be correct after assigning the newly created node to start, but when control returns to main, the new value is not saved.

typedef struct node
{
    int data;
    struct node *link;
}node;

node* createList(int data)
{
    node *tempNode=(node*)malloc(sizeof(node));
    tempNode->data=data;
    tempNode->link=NULL;
    return tempNode;
}

void addAtBegin(node *start,int data)
{
    node *addedNode=(node *)malloc(sizeof(node));
    addedNode->data=data;
    addedNode->link=(start==NULL)?NULL:start;
    start=addedNode;
}

void displayNodes(node *start)
{
    node *startCopy=start;
    while(startCopy!=NULL)
    {
        printf("%d\t",startCopy->data);
        startCopy=startCopy->link;
    }
    printf("\n");
}

int main( )
{   
    node *start=createList(2);
    addAtBegin(start,1);
    displayNodes(start);
    return 0;
}

Answer 1

Looks like another list question to me, with the same answer as most of them – start should be a pointer to a pointer.