Linked List in C - 4

linkedlis.c

#include <stdio.h>
 
typedef struct node {
    int val;
    struct node * next;
} node_t;
void print(node_t * head) {
    node_t * current = head;
    printf("***The list begins***\n");
    while (current != NULL) {
        printf("%d\n", current->val);
        current = current->next;
    }
    printf("***The list ends***\n");
}
void push_pichone(node_t * head) {
    printf("Enter the integer: ");
    int n;
    scanf("%d", &n);
    node_t * current = head;
    // list er shes element ta khuje ber korbo
    while (current->next != NULL) {
        current = current->next;
    }
 
    // ebar amra variable add korbo
    current->next = malloc(sizeof(node_t)); // malloc use kora khub e important
    current->next->val = n;
    current->next->next = NULL;
}
void push_shamne(node_t ** head) {
    printf("Enter the integer: ");
    int n;
    scanf("%d", &n);
    // notun node
    node_t * new_node;
    new_node = malloc(sizeof(node_t));
    // node er value
    new_node->val = n;
    new_node->next = *head;
    // head er value bodle dicchi
    *head = new_node;
}
int pop_shamne(node_t ** head) {
    int ret = -1;
    node_t * next_node = NULL;
    // eta korchi jaate
    if (*head == NULL) {
        return -1;
    }
 
    next_node = (*head)->next; // head variable er next address ta rakhtichi save kore
    ret = (*head)->val; // value ta save kore rakhtichi jaate pore return korte pari
    free(*head); // memory free kore dicchi
    *head = next_node; // head hishebe shei purono store kora address ta set kortichi
 
    return ret;
}
void menu(node_t *head) {
    int n;
    printf("What operation do you want to execute?\n");
    printf("Press 1 to print all elements.\n");
    printf("Press 2 to enter an integer at the end of the list.\n");
    printf("Press 3 to enter an integer at the beginning of the list.\n");
    printf("Press 4 to remove the first item.\n");
    printf("Press 0 to exit.\n");
    scanf("%d", &n);
    switch(n) {
        case 1:
            print(head);
            break;
        case 2:
            push_pichone(head);
            break;
        case 3:
            push_shamne(&head);
            break;
        case 4:
            printf("The removed element: %d\n", pop_shamne(&head));
            break;
    }
    if (n!=0) menu(head);
}
int main() {
    node_t *head = NULL;
    head = malloc(sizeof(node_t));
    int num;
    printf("Enter the first integer: ");
    scanf("%d", &num);
    head->val = num; // head er address e jei node ta ache tar val er man rakhlam num
    head->next = NULL; // porer address hishebe rakhlam NULL. orthat ekhanei shes
 
    menu(head);
    return 0;
}