Question

So I’m just wondering if this push function, which pushes a new value to the top a linked list stack is correct

void push(node** hd, int v){
node temp;
temp = (node*)malloc(sizeof(node));
temp -> val = v;
temp -> next = *hd;
*hd = temp;

}

Thanks in advance!

Also I’m wondering how I would make a pop function, to pop the most recently pushed value off of the stack.

The struct code looks like this by the way…

typedef struct nodeStruct
{
int val;
struct nodeStruct* next;
}node;

typedef node* list;

Answer 1

Dont define pointer types. They are confusing. Define a normal type and dereference it explicitly. Here is what you were trying to do without the pointer types.

#include <stdlib.h>
#include <stdio.h>

typedef struct nodeStruct
{
    int val;
    struct nodeStruct *next;
} node;

static void push(node **head, int v)
{
    node *temp = malloc(sizeof(node));
    temp->val = v;
    temp->next = *head;
    *head = temp;
}

int main(int argc, char **argv)
{
    (void) argv;
    (void) argc;
    node *list = NULL;

    for (int i=0; i<10; ++i) {
        push(&list, i);
    }
    for(node *l = list; l != NULL; l = l->next) {
        printf("%d ", l->val);
    }
    printf("\n");
    return 0;
}

Note that you should check for failure of malloc. In other words, malloc can return NULL, which should be handled – left to you.