Singly linked list in C

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

typedef struct Node ListNode;

struct Node {
       int element;
       ListNode *next;
};

void initialize_list (ListNode **head) {
     *head = NULL;
}

void add_element (ListNode **head, int element_data) {
     ListNode *new_node;
     new_node = (ListNode *)malloc(sizeof(ListNode));
     new_node -> element = element_data;
     new_node -> next = NULL;

     if (*head == NULL) {
        *head = new_node;
        return;
     }

     ListNode *current;
     current = *head;

     while (current -> next != NULL) {
           current = current -> next;
     }

     current -> next = new_node;
}

void delete_element (ListNode **head, int element_data) {
     ListNode *current;
     ListNode *previous;

     previous = *head;
     current = *head;

     while (current != NULL) {
           if (current -> element == element_data) {
                   if (previous != current) {
                       previous -> next = current -> next;
                   }
                   else {
                       *head = current -> next;
                   }

                   free(current);
                   return;
           }

           previous = current;
           current = current -> next;
     }
}

void print_list (ListNode **head) {
     ListNode *current;
     current = *head;

     int i = 0;

     while (current != NULL) {
           printf("Singly_linked_list[%d] == %d \n", i, current -> element);
           ++i;
           current = current -> next;
     }

     printf("\n");
}

int main()
{
    ListNode *head;
    initialize_list(&head);

    add_element(&head, 23);
    add_element(&head, 4);
    add_element(&head, 1);

    print_list(&head);

    delete_element(&head, 1);

    print_list(&head);

    add_element(&head, 7);
    add_element(&head, 2);

    print_list(&head);

    system("PAUSE");
    return 0;
}