求大神解答，为什么链表的节点free不了，不加倒没事，一加就报。

[暴打章鱼哥]

代码如下，大神就解答

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

struct info{

int num;
char name[100];

struct info * pnext;

};


void add(struct info **phead,int num,char name[100]){//增加节点

if ((*phead)==NULL){


(*phead) = (struct info * )malloc(sizeof(struct info));

(*phead)->num = num;

strcpy((*phead)->name, name);

(*phead)->pnext = NULL;





} else{

struct info *p = *phead;

while (p->pnext != NULL){

p=p->pnext;
}

struct info *pp = (struct info *)malloc(sizeof(struct info));

pp->num = num;

strcpy(pp->name, name);

pp->pnext = NULL;

p->pnext = pp;

}

}

void Modify(struct info **phead,int num,char oldname[100]){//修改节点


struct info * p = (*phead);

while( p->pnext != NULL){

if (p->num == num){
strcpy(p->name, oldname);
break;
}
p = p->pnext;
}

}

void delet(struct info **phead, int num){//删除节点

struct info *p = (*phead);

struct info * qq=NULL;//记录前一个节点的地址

while (p->pnext != NULL){

if (p->num == num){

qq->pnext = p->pnext;

free(p);


}

qq = p;
p = p->pnext;



}



}


int main(void){

struct info * phead=NULL;

add(&phead,1,"jjjjj");

add(&phead, 2, "jjkkj");

add(&phead, 3, "jjhmj");

Modify(&phead,2,"hahahahhahaha");

delet(&phead, 2);

printf("\n %d %s", phead->num, phead->name);
printf("\n %d %s", phead->pnext->num, phead->pnext->name);
//printf("\n %d %s", phead->pnext->pnext->num, phead->pnext->pnext->name);


system("pause");



}

[zhouqunhai]

明显逻辑有问题

[xueyu人生]

1.modify最后一个数据查询不到，修改如下： while( p != NULL){ if (p->num == num){ strcpy(p->name, oldname); break; } p = p->pnext; } 2.删除时，上面查找到后free（p）,p都释放了，下面p = p->pnext;当然会出问题，还有些逻辑错误，你自己理理，我有别的事要看看。

[冷风1023]

感觉删除的逻辑有问题，测试下吧。

[轻箬笠]

存在两个问题，代码如下

void delet(struct info **phead, int num) 
{//删除节点
    struct info *p = (*phead);
    struct info * qq = NULL;//记录前一个节点的地址  

    while (p->pnext != NULL) {
        if (p->num == num) {
            if (qq)//这里需要判断当前节点是否有前一个节点
                qq->pnext = p->pnext;
            else
                *phead = p->pnext;

            free(p);
            break;//这里需要退出循环
        }

        qq = p;
        p = p->pnext;
    }
}

[赵4老师]

数据结构对单链表进行数据排序 http://bbs.csdn.net/topics/392201633