example.c

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

typedef struct node {
    int key;
    struct node *next;
} node_t;


// Initialize first element of the list
node_t *init_st(int value){
    node_t *list = (node_t*)malloc(sizeof(node_t));
    if (list == NULL){
        printf("I CANT!\n");
        return NULL;
    }

    list->key = value;
    list->next = NULL;
    return list;
}

int is_empty(node_t *list){
  return list == NULL ? 1 : 0;
}

// Add element to the end of the list
void push(node_t *list, int value){
    node_t *current = list;
    
    // Iterate over list to find last
    while (current->next != NULL){
        current = current->next;
    }
    // Allocate memory for new node
    current->next = (node_t*)malloc(sizeof(node_t));
    if (current->next == NULL){
        printf("Can't allocate a memory for new node.\n");
    } else {
        // Insert value and next node
        current->next->key = value;
        current->next->next = NULL;
        printf("Successfully pushed: %d\n", value);
    }
}

int main(){
  // Init list, first element with key 1
  node_t *head = init_st(1);
  push(head, 2);
  push(head, 3);
  
  free(head);
  return 0;
}