链表实现

最近期末了，时间宝贵啊！！！高数是磨我的小妖精~~~

之前学过链表，但是没实现过，最近上C语言课开始讲链表了，所以我还是实现了一下。

链表的前提便是struct，在我的想法里，链表就是结构体的嵌套，是我们最开始的基础数据结构之一，其构成便是数据域与指针域，正因为开辟了指针域，所以链表比数组的缺点就是耗空间。

下面是单链表的实现代码，双链表期末后找时间写。

最近编译器被我玩坏了，先用C写，C++其实也一样，里面的输出语句就是我调试时的标志。

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

typedef struct node{
    int data;
    struct node *next; //C++可以不加struct 
}node;

node* initlist (int num){
    node *head = NULL;
    head = (node*)malloc(sizeof(struct node));
    head->data = num;
    head->next = NULL; 
    printf("init link-list OK!\n");
    return head;
}


void addelement(node *list,int num){
    node* tpre = list;
    while(tpre->next!=NULL)
        tpre = tpre->next;
    tpre->next = (node*)malloc(sizeof(struct node));
    tpre = tpre->next;
    tpre->data = num;
    tpre->next = NULL;
    printf("Add num:%d OK !\n",num);
    return ;
}

void delete_element(node *list,int num){
    node *tpre = NULL;
    node *tnow = list;
    while(tnow!=NULL){
        if(tnow->data==num){
            node *temp = tnow;
            tnow = tnow->next;
            free(temp);
            tpre->next = tnow;
            printf("delete %d OK!\n",num);
            return;
        }
        tpre = tnow;
        tnow = tnow->next;
    }
    printf("DEL Data:%d Erorr !\n",num);
    return ;
}

void changevalue(node *list,int num,int cnum){
    node *tnext = list;
    while(tnext != NULL){
        if(tnext->data==num){
            tnext->data = cnum;
            printf("Change data: %d to %d OK!\n",num,cnum);
            return;
        }
        tnext = tnext->next;
    }  
    printf("CHA Data: %d to %d Erorr !\n",num,cnum);
    return;
}

void freelinklist(node *list){
    node *tre = list;
    node *tnext = list->next;
    while(tnext != NULL){
        tnext = tnext->next;
        free(tre);
        tre = tnext; 
    }
    printf("FREE OK!\n");
    return ;
}

void showlinklist(node *list){
    node *tpre = list;
    while(tpre->next != NULL){
        printf("%d ",tpre->data);
        tpre = tpre->next;
    }
    printf("%d #\n",tpre->data);
    printf("Showing-Finish!\n");
    return ;
}

int main(){
    node *list = initlist(1);
    addelement(list,2);
    addelement(list,3);
    addelement(list,4);
    addelement(list,5);
    addelement(list,6);
    changevalue(list,6,7);
    changevalue(list,6,8);
    delete_element(list,3);
    delete_element(list,9);
    showlinklist(list);
    freelinklist(list);
    return 0;
}