如何解决 C 中的堆栈问题？

Question

i made Global Variables

struct node* top;

struct node {
    char x;
    struct node* next;
};

it is struct node

struct node* newnode(char x) {
    struct node* new1 = (struct node*)malloc(sizeof(struct node));
    new1->x = x;
    new1->next = NULL;
    return new1;
}

and i Initialized top=NULL;

ex) push(top, a)

void push(struct node* h, char c) {
    struct node* new1 = newnode(c);

    if (count(h) > N) {
        printf("Stack FULL\n");
        return;
    }
    new1->next = h;
    h= new1;

}

Then shouldn't the address value of top be the address value of new1 after the push function?

Even after the push function ends, the top remains NULL, so I don't know what to do.

Please give me some advice!

Answer 1

You are passing the value in top , so the function cannot change what is in top . You can either pass a pointer to top , or have the function return the new value you want for top so that the caller can assign it to top .