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Interactive C program to implement Instert begining, delete begining and reversing of single linked list

shiv@ubuntu:~/ds/list$ cat   revlist.c
/*
 * Interactive C program to simulate following operations
 * on single linked list
 * 1. insert begining of the list
 * 2. display data in the list (traversing)
 * 3. delete element at begining of the list
 * 4. reverse the elements in single linked list
 */

#include<stdio.h>
#include<stdlib.h>
struct list
{
int data;
struct list *next;
};
typedef struct list *L;

/* function to insert element into list */

void insert(L *head)
{
 /* look for typedef temp is pointer not variable,
  *  same will apply to all
  */
 L temp;

 temp=malloc(sizeof(struct list));
 if(!temp) {
    printf("Can't allocate memory\n");
    return;
 }

 printf("Enter element to insert\n");
 scanf("%d", &temp->data);
 temp->next = NULL;

 if(*head == NULL) {
    *head = temp;
 } else {

    temp->next = *head;
    *head = temp;
 }
}

/* function to display elements in the list */

void display(L head)
{
  L temp;
  
  temp = head;
  if(temp == NULL){
     printf("Empty list \n");
     return;
  }

 printf("List elements are \n");
 while(temp) {
     printf("%d\n", temp->data);
     temp = temp->next;
 }

}

/* function to delete elements in the list */

void del(L *head)
{
  L temp;

 if(*head == NULL) {
    printf("No elements to delete, Empty list\n");
    return;
 }

 temp =*head;
 printf("Element deleted %d\n", temp->data);
 *head =(*head)->next;
 /* release the memory once deleted */
 free(temp);

}

/* function to reverse elements in list */

void reverse(L *head)
{
  L temp, t, rev=NULL;
  temp = *head;
 
  while(temp != NULL) {
        t = temp;
        /* first we need to move the list before modifying it */
        temp = temp->next;
        t->next = rev;
        rev  = t;
  }

  /* change head to point reversed list */
  *head =rev;
}


/* Main function to help test list operations */

int main()
{
 L head = NULL;
 int ch;

 while(1) {
 system("clear");
 printf("1 Insert\n2 Display\n3 del\n4 reverse\n5 exit\n");
 printf("Enter your choice\n");
 scanf("%d", &ch);
 switch(ch) {
    case 1: insert(&head); break;
    case 2: display(head); break;
    case 3: del(&head); break;
    case 4: reverse(&head); break;
    case 5: exit(0);
    default: printf("Invalid choice\n");
 }
 getchar();
 getchar();
}
return 0;
}
/* end of  the program */
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