回调函数

　　有点类似模板的功能，可以使用函数指针作为参数，当调用函数时，使用void *进行传递参数，细致比较时，再用int *之类的进行强制转换。回调函数，其实就是在参数中定义函数，调用时，回到主函数去调用这个函数。仔细用法如下：

首先定义查找函数

Node * search_list(Node *node, void const *value, int (*compare)(void const *,void const *)){
    while(node!=NULL){
        if(compare(&node->data,value) == 0 )
            break;
        node = node->next;
    }
    return node;
}

比较函数

int compare_ints(void const *a,void const *b){
    if( *(int *)a == *(int *)b)
        return 0;
    else
        return 1;
}

函数中的调用

    int *desire = (int *)malloc(sizeof(int));
    *desire = 3;
    Node *n1 = (Node *)malloc(sizeof(Node)); 
    n1 = search_list(L->next,desire,compare_ints);
    if(n1!=NULL)
        printf("找到了%d",n1->data);

全部代码

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

typedef struct Node{
    int data;
    struct Node * next;
}Node;

void createList(Node * L,int len);
void showList(Node *L);
void clearList(Node *L);
void getNode(Node *L,int n,Node *tar);
int insertNode(Node *L,int n,int num);
int deleteNode(Node *L,int n);
Node * search_list(Node *node, void const *value, int (*compare)(void const *,void const *));
int compare_ints(void const *a,void const *b);

int main()
{
    Node *L= (Node *)malloc(sizeof(Node));

    createList(L,5);
    showList(L);

    Node *tar= (Node *)malloc(sizeof(Node));
    getNode(L,3,tar);
    printf("the third is:%d
",tar->data);
    
    if(insertNode(L,3,0))
        showList(L);
    
    printf("回调函数：
");
    int *desire = (int *)malloc(sizeof(int));
    *desire = 3;
    Node *n1 = (Node *)malloc(sizeof(Node)); 
    n1 = search_list(L->next,desire,compare_ints);
    if(n1!=NULL)
        printf("找到了%d",n1->data);

    /*
    if(deleteNode(L,3))
        showList(L);

    clearList(L);
    showList(L);
    */

    /**desire = 9;
    Node *n2 = search_list(L,desire,compare_ints);
    if(n2!=NULL)
        printf("找到了%d",n2->data);
    *desire = 7;
    Node *n3 = search_list(L,desire,compare_ints);
    if(n3!=NULL)
        printf("找到了%d",n3->data);*/
    getchar();
    return 0;
}
Node * search_list(Node *node, void const *value, int (*compare)(void const *,void const *)){
    while(node!=NULL){
        if(compare(&node->data,value) == 0 )
            break;
        node = node->next;
    }
    return node;
}
int compare_ints(void const *a,void const *b){
    if( *(int *)a == *(int *)b)
        return 0;
    else
        return 1;
}

void createList(Node * L,int len){
    int i;
    Node * p;
    L->next = NULL;
    for(i=0;i<len;i++){
        p = (Node *)malloc(sizeof(Node));
        p->data = 2*i+1;
        p->next = L->next;
        L->next = p;
    }
}

void showList(Node *L){
    Node *p = (Node *)malloc(sizeof(Node));
    p=L->next;
    while(p){
        printf("%d->",p->data);
        p=p->next;
    }
    printf("null
");
    free(p);
}

void clearList(Node *L){
    Node *p,*q;
    p=L->next;
    while(p){
        q=p->next;
        free(p);
        p=q;
    }
    L->next=NULL;
}

void getNode(Node *L,int n,Node *tar){
    int i=1;
    Node *p;
    p=L->next;
    while(p && i<n){
        p=p->next;
        i++;
    }
    if(!p || i>n)
        printf("error!");
    tar->data=p->data;
}

int insertNode(Node *L,int n,int num){
    int i=1;
    Node *p = L->next;
    while( p && i<n-1){
        p=p->next;
        i++;
    }
    if(!p || i>n-1)
        return 0;
    Node *q = (Node *)malloc(sizeof(Node));
    q->data = num;
    q->next = p->next;
    p->next = q;
    return 1;
}

int deleteNode(Node *L,int n){
    int i=1;
    Node *p = L->next;
    Node *q;
    while( p->next && i<n-1){
        p=p->next;
        i++;
    }
    if( !(p->next) || i>n-1)
        return 0;
    q=p->next;
    p->next = q->next;
    free(q);
    return 1;
}

运行示例