简单链表设计

为准备找工作笔试的练习。
basedefine.h

#ifndef BASEDEFINE_H_INCLUDED
#define BASEDEFINE_H_INCLUDED

typedef int Elem;
typedef struct tagNode {
    Elem element;
    struct tagNode* next;
} Node,*Linklist;

Linklist create();

void destroy(Linklist &L);
bool isEmpty(Linklist L);
int getLength(Linklist L);
bool insert(Linklist L,Elem e,int pos=0);
void deletenode(Linklist L,int pos);
void visitall(Linklist L);



#endif // BASEDEFINE_H_INCLUDED



main.cpp

#include <iostream>
#include "basedefine.h"

using namespace std;
Linklist create() //建立空表

{
    Linklist L;
    if((L =(Linklist) malloc(sizeof(Node)))==NULL)
        cout<<"ERROR"<<endl;
    L->element = 0;
    L->next= NULL;
    return L;
}

void destroy(Linklist &L)
{
    if(L==NULL) {
        cout<<"Null List"<<endl;
        return;
    }
    Node* pre=L;
    Node* now;
    while((now=pre->next)!=NULL){
        free(pre);
        pre = now;
    }
    free(now);
    L=NULL;
}


bool isEmpty(Linklist L)
{
    if(L==NULL) {
        cout<<"Null List"<<endl;
        return true;
    }
    if(L->next==NULL)
        return true;
    return false;
}
int getLength(Linklist L)
{
    if(isEmpty(L))
        return 0;
    int i;
    Node* node=L;
    for(i=0;node->next!=NULL;i++)
        node = node->next;
    return i;
}



bool insert(Linklist L,Elem e,int pos)//在pos位置后插入e，默认在头节点后

{
    if(L==NULL) {
        cout<<"Null List"<<endl;
        return false;
    }
    int i=0;
    Node* tmp;
    Linklist pre=L;

    if(pos<0){
            cout<<"Wrong position"<<endl;
            return false;
    }
    while(pre->next!=NULL && i<pos) {
        i++;
        pre = pre->next;
    }
    if(i==pos) {
        tmp = (Node*)malloc(sizeof(Node));
        if(tmp==NULL)
            return false;
        tmp->element = e;
        tmp->next = pre->next;
        pre->next = tmp;
    }else //在末尾了

        if(pos==i+1) { //刚好在末尾插入

            tmp = (Node*)malloc(sizeof(Node));
            if(tmp==NULL)
                return false;
            tmp->element = e;
            tmp->next = NULL;
            pre->next = tmp;
        }else {
            cout<<"Wrong position"<<endl;
            return false;
        }
    return true;
}

void deletenode(Linklist L,int pos)
{
    if(pos>getLength(L) || pos<1 || L==NULL)
        return;
    int i;
    Node* pre=L;
    for(i=0;i<pos-1;i++) //获得pos前面那个元素的指针

        pre = pre->next;
    Node* posnode=pre->next;
    if(posnode->next==NULL) { //刚好是删除尾元素

        pre->next=NULL;
        free(posnode);
    }else {
        pre->next = posnode->next;
        free(posnode);
    }

}
void visitall(Linklist L) //遍历链表

{
    if(L==NULL) return;
    Node* p=L;
    while(p->next!=NULL) {
        p=p->next;
        cout<<p->element<<endl;
    }
}

int main()
{
    Linklist L1=NULL;
    L1=create();
    insert(L1,2);
    insert(L1,6);
    insert(L1,7);
    //destroy(L1);

    insert(L1,28);
    visitall(L1);
    cout<<"Length is "<<getLength(L1)<<endl;

    deletenode(L1,2);
        visitall(L1);
    cout<<"Length is "<<getLength(L1)<<endl;
    destroy(L1);
    deletenode(L1,3);
        visitall(L1);
    cout<<"Length is "<<getLength(L1)<<endl;
    return 0;
}