今天繼續完善自己的鏈表，上次已經實現了鏈表的插入、遍歷、銷毀方法，對于鏈表的插入，我們上次是在頭結點進行插入的，這次，我們來實現一個在任意結點進行插入的方法。

實現鏈表的另外一種插入方法----在任意位置進行插入:

?在實現它之前，先實現獲取任意位置的結點的函數，為便在實現任意插入時會使用到它，先在頭文件中定義：

list.h:

#ifndef _LIST_H_ #define _LIST_H_#include <assert.h>typedef struct node {int data;struct node* next; } node_t;typedef void (*FUNC)(node_t*);node_t* list_insert_front(node_t* head, int data);void list_for_each(node_t* head, FUNC f);node_t* list_free(node_t* head);node_t* list_get_node(node_t* head, int index);//獲取指定位置的結點#endif /* _LIST_H_ */

具體實現list.c:

#include "list.h" #include <stdlib.h>node_t* list_insert_front(node_t* head, int data) {node_t* n = (node_t*)malloc(sizeof(node_t));assert(n != NULL);n->data = data;n->next = NULL;if (head == NULL)head = n;else{n->next = head;head = n;}return head; }void list_for_each(node_t* head, FUNC f) {while (head){f(head);head = head->next;} }node_t* list_free(node_t* head) {node_t* tmp;while (head){tmp = head;head = head->next;free(tmp);}return head; }node_t* list_get_node(node_t* head, int index) {assert(index >= 0);int j = 0;while (head && j < index){head = head->next;j++;}if (j == index)//說明已經找到結點return head;return head;//說明最終head指向NULL,沒有找到結點}

上面的也可簡寫：

node_t* list_get_node(node_t* head, int index) {assert(index >= 0);int j = 0;while (head && j < index){head = head->next;j++;}return head;}

測試一下：

main.c:

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_free(head);assert(head == NULL);return 0; }

編譯運行：

如果沒有找到呢？

main.c:

int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 5);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_free(head);assert(head == NULL);return 0; }

編譯運行：

好了，接著正式來定義任意插入的函數：

list.h:

#ifndef _LIST_H_ #define _LIST_H_#include <assert.h>typedef struct node {int data;struct node* next; } node_t;typedef void (*FUNC)(node_t*);node_t* list_insert_front(node_t* head, int data);void list_for_each(node_t* head, FUNC f);node_t* list_free(node_t* head);node_t* list_get_node(node_t* head, int index);node_t* list_insert_at(node_t* head, int data, int index);#endif /* _LIST_H_ */

list.c:

#include "list.h" #include <stdlib.h>node_t* list_insert_front(node_t* head, int data) {node_t* n = (node_t*)malloc(sizeof(node_t));assert(n != NULL);n->data = data;n->next = NULL;if (head == NULL)head = n;else{n->next = head;head = n;}return head; }void list_for_each(node_t* head, FUNC f) {while (head){f(head);head = head->next;} }node_t* list_free(node_t* head) {node_t* tmp;while (head){tmp = head;head = head->next;free(tmp);}return head; }node_t* list_get_node(node_t* head, int index) {assert(index >= 0);int j = 0;while (head && j < index){head = head->next;j++;}return head;}node_t* list_insert_at(node_t* head, int data, int index) {assert(index >= 0);if (index == 0)//等于就是頭插入結點，直接調用現成的方法return list_insert_front(head, data);node_t* p;p = list_get_node(head, index - 1);if (p == NULL){fprintf(stderr, "error insert pos\n");exit(EXIT_FAILURE);}
　　//新建一個節點node_t* n = (node_t*)malloc(sizeof(node_t));assert(n != NULL);n->data = data;n->next = NULL;
　　//將節點進行鏈接n->next = p->next;p->next = n;return head; }

說明：

①fprintf表示向什么地方輸出，如fprintf(stdio,"hello!");等價于printf("hello!");

②exit()表示程序退出，參數EXIT_FAILURE代表錯誤退出，它還有另外一個宏定義EXIT_SUCCESS，代表成功退出

程序測試：

main.c:

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_insert_at(head, 15, 1);list_for_each(head, print_node);putchar('\n');head = list_free(head);assert(head == NULL);return 0; }

編譯：

其中的fprintf需要頭文件：

所以在list.c中加入此頭文件：

再次編譯，運行：

如果插入失敗會怎樣呢？

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_insert_at(head, 15, 5);//這個位置沒有元素，應該會插入失敗list_for_each(head, print_node);putchar('\n');head = list_free(head);assert(head == NULL);return 0; }

編譯運行：

實現鏈表的刪除方法：

先定義刪除方法：

list.h:

?

#ifndef _LIST_H_ #define _LIST_H_#include <assert.h>typedef struct node {int data;struct node* next; } node_t;typedef void (*FUNC)(node_t*);node_t* list_insert_front(node_t* head, int data);void list_for_each(node_t* head, FUNC f);node_t* list_free(node_t* head);node_t* list_get_node(node_t* head, int index);node_t* list_insert_at(node_t* head, int data, int index);node_t* list_remove_at(node_t* head, int index);#endif /* _LIST_H_ */

?

具體實現，在實現前，先用一個簡單的圖來解釋下：

具體實現如下list.c:

node_t* list_remove_at(node_t* head, int index) {assert(index >= 0);node_t* n;if (index == 0)//這是移除首結點{n = head;head = head->next;free(n);}else{node_t* p = list_get_node(head, index - 1);if (p == NULL || p->next == NULL){fprintf(stderr, "error remove pos\n");exit(EXIT_FAILURE);}n = p->next;p->next = n->next;free(n);}return head; }

測試一下main.c:

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_insert_at(head, 15, 1);list_for_each(head, print_node);putchar('\n');head = list_remove_at(head, 1);list_for_each(head, print_node);putchar('\n');head = list_free(head);assert(head == NULL);return 0; }

編譯運行：

如果移除的元素不存在呢？

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_insert_at(head, 15, 1);list_for_each(head, print_node);putchar('\n');head = list_remove_at(head, 5);//這個元素不存在，移除時會出錯list_for_each(head, print_node);putchar('\n');head = list_free(head);assert(head == NULL);return 0; }

運行：

實現鏈表的查找方法：

list.h:

?

#ifndef _LIST_H_ #define _LIST_H_#include <assert.h>typedef struct node {int data;struct node* next; } node_t;typedef void (*FUNC)(node_t*);node_t* list_insert_front(node_t* head, int data);void list_for_each(node_t* head, FUNC f);node_t* list_free(node_t* head);node_t* list_get_node(node_t* head, int index);node_t* list_insert_at(node_t* head, int data, int index);node_t* list_remove_at(node_t* head, int index);node_t* list_find(node_t* head, int data, int* ret);//ret代表找到的鏈表的索引位置，返回值代表找到的鏈表結點#endif /* _LIST_H_ */

?

list.c:

#include "list.h" #include <stdlib.h> #include <stdio.h>node_t* list_insert_front(node_t* head, int data) {node_t* n = (node_t*)malloc(sizeof(node_t));assert(n != NULL);n->data = data;n->next = NULL;if (head == NULL)head = n;else{n->next = head;head = n;}return head; }void list_for_each(node_t* head, FUNC f) {while (head){f(head);head = head->next;} }node_t* list_free(node_t* head) {node_t* tmp;while (head){tmp = head;head = head->next;free(tmp);}return head; }node_t* list_get_node(node_t* head, int index) {assert(index >= 0);int j = 0;while (head && j < index){head = head->next;j++;}return head;}node_t* list_insert_at(node_t* head, int data, int index) {assert(index >= 0);if (index == 0)return list_insert_front(head, data);node_t* p;p = list_get_node(head, index - 1);if (p == NULL){fprintf(stderr, "error insert pos\n");exit(EXIT_FAILURE);}node_t* n = (node_t*)malloc(sizeof(node_t));assert(n != NULL);n->data = data;n->next = NULL;n->next = p->next;p->next = n;return head; }node_t* list_remove_at(node_t* head, int index) {assert(index >= 0);node_t* n;if (index == 0){n = head;head = head->next;free(n);}else{node_t* p = list_get_node(head, index - 1);if (p == NULL || p->next == NULL){fprintf(stderr, "error remove pos\n");exit(EXIT_FAILURE);}n = p->next;p->next = n->next;free(n);}return head; }node_t* list_find(node_t* head, int data, int* ret) {*ret = -1;int i = 0;while (head){if (head->data == data){*ret = i;break;}head = head->next;i++;}return head; }

測試main.c:

#include "list.h" #include <stdio.h>void print_node(node_t* n) {printf("data=%d ", n->data); }int main(void) {node_t* head = NULL;head = list_insert_front(head, 30);head = list_insert_front(head, 20);head = list_insert_front(head, 10);list_for_each(head, print_node);putchar('\n');node_t* n = NULL;n = list_get_node(head, 1);if (n != NULL)printf("data = %d\n", n->data);elseprintf("not found\n");head = list_insert_at(head, 15, 1);list_for_each(head, print_node);putchar('\n');head = list_remove_at(head, 1);list_for_each(head, print_node);putchar('\n');int ret;n = list_find(head, 20, &ret);if (n != NULL)printf("data = %d index = %d\n", n->data, ret);elseprintf("not found\n");head = list_free(head);assert(head == NULL);return 0; }

編譯，運行：

好了，今天的學習到這，關于鏈表，下次會再次進行完善，下次見。

?

轉載于:https://www.cnblogs.com/webor2006/p/3484812.html

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