鏈表實例程序（C語言）

下面是用 C語言來實現鏈表的一個實例程序，具體細節如下：

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

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

struct node *head = NULL;
struct node *current = NULL;

//display the list
void printList(){
struct node *ptr = head;
printf("\n[ ");

//start from the beginning
while(ptr != NULL){
printf("(%d,%d) ",ptr->key,ptr->data);
ptr = ptr->next;
}
printf(" ]");
}

//insert link at the first location
void insertFirst(int key, int data){
//create a link
struct node *link = (struct node*) malloc(sizeof(struct node));
link->key = key;
link->data = data;

//point it to old first node
link->next = head;

//point first to new first node
head = link;
}

//delete first item
struct node* deleteFirst(){
//save reference to first link
struct node *tempLink = head;

//mark next to first link as first
head = head->next;

//return the deleted link
return tempLink;
}

//is list empty
bool isEmpty(){
return head == NULL;
}

int length(){
int length = 0;
struct node *current;

for(current = head; current!=NULL; current = current->next){
length++;
}
return length;
}

//find a link with given key
struct node* find(int key){
//start from the first link
struct node* current = head;

//if list is empty
if(head == NULL){
return NULL;
}

//navigate through list
while(current->key != key){

  //if it is last node
  if(current->next == NULL){
     return NULL;
  }else{
     //go to next link
     current = current->next;
  }

}
//if data found, return the current Link
return current;
}

//delete a link with given key
struct node* delete(int key){
//start from the first link
struct node* current = head;
struct node* previous = NULL;

//if list is empty
if(head == NULL){
return NULL;
}

//navigate through list
while(current->key != key){

  //if it is last node
  if(current->next == NULL){
     return NULL;
  }else{
     //store reference to current link
     previous = current;
     //move to next link
     current = current->next;             
  }

}

//found a match, update the link
if(current == head) {
//change first to point to next link
head = head->next;
}else {
//bypass the current link
previous->next = current->next;
}
return current;
}

void sort(){

int i, j, k, tempKey, tempData ;
struct node *current;
struct node *next;
int size = length();
k = size ;

for ( i = 0 ; i < size - 1 ; i++, k-- ) {
current = head ;
next = head->next ;

  for ( j = 1 ; j < k ; j++ ) {   

     if ( current->data > next->data ) {
        tempData = current->data ;
        current->data = next->data;
        next->data = tempData ;

        tempKey = current->key;
        current->key = next->key;
        next->key = tempKey;
     }

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

}
}

void reverse(struct node** head_ref) {
struct node* prev = NULL;
struct node* current = *head_ref;
struct node* next;

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

main() {

insertFirst(1,10);
insertFirst(2,20);
insertFirst(3,30);
insertFirst(4,1);
insertFirst(5,40);
insertFirst(6,56);

printf("Original List: ");

//print list
printList();

while(!isEmpty()){
struct node *temp = deleteFirst();
printf("\nDeleted value:");
printf("(%d,%d) ",temp->key,temp->data);
}

printf("\nList after deleting all items: ");
printList();
insertFirst(1,10);
insertFirst(2,20);
insertFirst(3,30);
insertFirst(4,1);
insertFirst(5,40);
insertFirst(6,56);
printf("\nRestored List: ");
printList();
printf("\n");

struct node *foundLink = find(4);

if(foundLink != NULL){
printf("Element found: ");
printf("(%d,%d) ",foundLink->key,foundLink->data);
printf("\n");
}else{
printf("Element not found.");
}

delete(4);
printf("List after deleting an item: ");
printList();
printf("\n");
foundLink = find(4);

if(foundLink != NULL){
printf("Element found: ");
printf("(%d,%d) ",foundLink->key,foundLink->data);
printf("\n");
}else{
printf("Element not found.");
}

printf("\n");
sort();
printf("List after sorting the data: ");
printList();
reverse(&head);
printf("\nList after reversing the data: ");
printList();
}

如果我們編譯並運行上述程序，那麼這將產生以下結果 -

Original List:
[ (6,56) (5,40) (4,1) (3,30) (2,20) (1,10) ]
Deleted value:(6,56)
Deleted value:(5,40)
Deleted value:(4,1)
Deleted value:(3,30)
Deleted value:(2,20)
Deleted value:(1,10)
List after deleting all items:
[ ]
Restored List:
[ (6,56) (5,40) (4,1) (3,30) (2,20) (1,10) ]
Element found: (4,1)
List after deleting an item:
[ (6,56) (5,40) (3,30) (2,20) (1,10) ]
Element not found.
List after sorting the data:
[ (1,10) (2,20) (3,30) (5,40) (6,56) ]
List after reversing the data:
[ (6,56) (5,40) (3,30) (2,20) (1,10) ]

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