请用C语言写一个单链表程序

好的，以下是一个简单的单链表程序示例，使用C语言编写：

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

struct node {
int data;
struct node* next;
};

int main() {
struct node* head = NULL;
struct node* second = NULL;
struct node* third = NULL;

// allocate 3 nodes in the heap
head = (struct node*)malloc(sizeof(struct node));
second = (struct node*)malloc(sizeof(struct node));
third = (struct node*)malloc(sizeof(struct node));

// assign data to 1st node
head->data = 1;

// link the 1st node with the 2nd node
head->next = second;

// assign data to 2nd node
second->data = 2;

// link the 2nd node with the 3rd node
second->next = third;

// assign data to 3rd node
third->data = 3;

// terminate the 3rd node with a NULL pointer
third->next = NULL;

// display the list
struct node* ptr = head;
while (ptr != NULL) {
printf("%d -> ", ptr->data);
ptr = ptr->next;
}
printf("NULL");

return 0;
}