指针，函数指针，结构体，链表

• 指针

指针数组：很多指针的数组

数组指针：指向数组的指针

int arr [10];

arr 首元素地址

&arr  数组地址

• 函数指针

#include <stdio.h>

void Func();
void Func2(void (*p)());
int main()
{
    void (*p)() = &Func;
    void (*pp)(void (*c)()) = Func2;
    (*p)();
    (*pp)(*p);
}
void Func()
{
    printf("%s
","qwertyuio");
}
void Func2(void (*p)())
{
    (*p)();
}

应用函数指针实现对数组既可以升序也可以降序

#include <stdio.h>
#define LENGTH(arr) sizeof(arr)/sizeof(arr[0])

void BubbleSort(int* arr, int nLength,int(*fp)(int , int ));
int bigger(int , int );
int smaller(int ,int );
int Find(int* arr, int nLength,int num);

int main()
{
    int arr[10] = {1,2,3,4,5,6,7,8,9};
    int len = LENGTH(arr);
    //BubbleSort(arr,10,bigger);
    printf("%d
",len);
    printf("%d
", Find(arr,9,8));
    return 0;
}

void BubbleSort(int* arr, int nLength,int(*fp)(int , int ))
{
    int i;
    int j;
    int temp;
     for(i = 0 ; i < nLength - 1;i++)
     {
        for(j = i + 1; j < nLength; j++)
        {
            if(   (*fp)( arr[i] , arr[j])  )
            {
                temp = arr[j];
                arr[j] = arr[i];
                arr[i] = temp;
        }
        }
     }

    /*for(i=0;i<nLength-1;i++)
    {
        for(j=0;j<nLength-i-1;j++)
        {
            if(    (*fp)(arr[j] , arr[j+1])    )
            {
                temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }*/
}
int bigger(int a , int  b)
{
    return a > b;
}
int smaller(int a ,int b)
{
    return a < b;
}
int Find(int* arr, int nLength,int num)
{
    int left = 0;
    int right =nLength -1;
    int p = (left + right ) / 2;
    while(arr[p] != num)
    {
        if(arr[p] > num)
            right = p;
        else 
            left = p;
        p = (left + right ) / 2;
    }
    return p;
}

• 结构体

第一种

struct NODE
{
    int xh;
    char* name;
    char* phone;
};
typedef struct NODE Node ;//起别名

第二种：

struct NODE
{
    int xh;
    char* name;
    char* phone;
}Node;

可通过结构体地址修改其成员变量

Node c = {3,"ccc","119"};
Node *p = &c;
p->name = "ppp";
printf("%s
", p->name);

 结构体对齐

• 链表

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

typedef struct NODE
{
    int xh;
    struct NODE  * pnext;//这里不能用别名，因为还没起。
}node;
void Addnode(node **, node**);
void Addindexnode(node **, node **,int );
void Traverse(node *);
void Delete(node** ,node** , int);
int getXh();
int main()
{
    node *pHead =    NULL;
    node *pEnd = NULL;
    Addnode(&pHead, &pEnd);
    Addnode(&pHead, &pEnd);
    Addnode(&pHead, &pEnd);
    Addnode(&pHead, &pEnd);
    Addindexnode(&pHead, &pEnd,4);
    Delete(&pHead ,&pEnd , 4);
    Traverse(pHead);
    return 0;
}
void Addnode(node **pHead,node **pEnd)
{
    //申请新节点
    node* temp = (node *)malloc(sizeof(node));
    temp->pnext = NULL;
    temp->xh = getXh();
    //第一次添加
    if(*pHead == NULL)
    {
        *pHead = temp;
        *pEnd = temp;
    }
    else 
    {
        (*pEnd)->pnext = temp;
        *pEnd = temp;
    }
}
void Addindexnode(node **pHead, node **pEnd,int index)
{
    node *bj = *pHead;
    node* temp = (node *)malloc(sizeof(node));
    temp->xh = getXh();
    temp->pnext = NULL;

    //头
    if((*pHead)->xh == index)
    {
        temp->pnext = *pHead;
        *pHead = temp;
        return ;
    }
    //中间
    //while(bj->pnext->xh != index &&bj->pnext != *pEnd)
    //{
    //    bj = bj->pnext;
    //}
    //if(bj->pnext->xh == index)
    //{
    //    temp->pnext = bj->pnext;
    //    bj->pnext = temp;
    //    return;
    //}


    //while(bj->pNext->xh != i)
    //{
    //    bj = bj->pNext;
    //    if(bj == *pEnd)            //尾添加
    //    {
    //        (*pEnd)->pNext = temp;
    //        *pEnd = temp;
    //        return;
    //    }
    //}
    //temp->pNext = bj->pNext;    //中间添加
    //bj->pNext = temp;
    //return;


    while(bj->pnext != NULL) //中间
    {
        if(bj->pnext->xh == index)
        {
            temp->pnext = bj->pnext;
            bj->pnext = temp;
            return;
        }
        bj = bj->pnext;
    }
    //尾
        (*pEnd)->pnext = temp;
        *pEnd = temp;
        return;
}
void Delete(node **pHead ,node** pEnd, int xh)
{
    node* bj = *pHead;
    node* p; 
    if((*pHead)->xh == xh)
    {
        *pHead = (*pHead)->pnext;
        bj = *pHead;
        return;
    }
    while(bj->pnext->pnext != NULL )
    {
        if(bj->pnext->xh == xh)
        {
            p = bj->pnext;
            bj->pnext = bj->pnext->pnext;    
            free(p);
            return;
        }
        bj = bj->pnext;
    }
    p = bj->pnext;
    free(p);
    bj->pnext = NULL;
    *pEnd = bj;
}
void Traverse(node *pHead)
{
    while(pHead != NULL)
    {
        printf("%d
",pHead->xh);
        pHead = pHead->pnext;
    }
}
int getXh()
{
    static int i = 1;
    return i++;
}