C示例程序删除单链表中的项目

#include <stdio.h>

#include <stdlib.h>



struct node {

   int data;

   struct node *next;

};



struct node *head = NULL;

struct node *current = NULL;

struct node *prev = NULL;



//Create Linked List

void insert(int data) {

   // Allocate memory for new node;

   struct node *link = (struct node*) malloc(sizeof(struct node));



   link->data = data;

   link->next = NULL;



   // If head is empty, create new list

   if(head==NULL) {

      head = link;

      return;

   }



   current = head;



   // move to the end of the list

   while(current->next!=NULL)

      current = current->next;



   // Insert link at the end of the list

   current->next = link;

}



void display() {

   struct node *ptr = head;



   printf("head] =>");

   //start from the beginning

   while(ptr != NULL) {        

      printf(" %d =>",ptr->data);

      ptr = ptr->next;

   }



   printf(" [null]\n");

}



void remove_data(int data) {

   int pos = 0;



   if(head==NULL) {

      printf("Linked List not initialized");

      return;

   }



   if(head->data == data) {

      if(head->next != NULL) {

         head = head->next;

         return;

      } else {

         head = NULL;

         printf("List is empty now");

         return;

      }

   } else if(head->data != data && head->next == NULL) {

      printf("%d not found in the list\n", data);

      return;

   }



// prev = head;

   current = head;



   while(current->next != NULL && current->data != data) {

      prev = current;

      current = current->next;

   }        



   if(current->data == data) {

      prev->next = prev->next->next;

      free(current);

   } else

      printf("%d not found in the list.", data);



}



int main() {

   insert(10);

   insert(20);

   insert(30);

   insert(1);

   insert(40);

   insert(56);



   printf("Before Removal : ");

   display();

   remove_data(30);

   printf("After Removal  : ");

   display();



   return 0;

}