链表释放老出错啊高手帮看看,该怎么解决

链表释放老出错啊高手帮看看

C/C++ code

#include <stdio.h>#include <stdlib.h>#include <string.h>typedef struct pst{    char ca;    struct pst *next;}PST;void*CreatHead(){    PST *P;    P = (PST *)malloc(sizeof(PST));    memset(P,0X00,sizeof(PST));    return P;}void Addnode(PST *add,PST *phead){    PST *p;//    p = phead->next;    while(phead ->next!=NULL)    {        p =phead->next;        phead = p;    }    phead ->next = add;    add->next=NULL;}void printl(PST *phead){        PST *p;    while(phead->next)    {        p = phead->next;        phead = p;        printf("%d\n",phead->ca);    }}void del(PST *phead){    PST *p,*q;    q = phead;   while(phead->next)     {     p = phead->next;     phead = p;        free(p);      }         free(q); //释放头；    q = NULL;}int main(void){    PST *Head,*Add;    int sc= 0,i;printf("create link Head\n");    Head = CreatHead();    printf("Input link NUmber:");    scanf("%d",&sc);    for(i = 1; i <= sc; i++)    {        Add = (PST *)malloc(sizeof(PST));        Add->ca = 10+i;        Addnode(Add,Head);   }printl(Head);printf("free link now:\n");del(Head);return 0;    }

C/C++ code

//将c:\\tmp文件夹下的所有文件的内容全部放到用malloc分配的内存中#include <stdio.h>#include <stdlib.h>#include <string.h>#include <io.h>struct FB {    char fn[256];    size_t fl;    char *b;    struct FB *next;    struct FB *prev;} *fh,*fb,*ft;char ln[256];char fpn[256];FILE *af;FILE *f;int L,n;int main() {    system("dir /b /a-d c:\\tmp\\*.* >c:\\allfn.txt");    af=fopen("c:\\allfn.txt","r");    if (NULL==af) {        printf("Can not open file c:\\allfn.txt!\n");        return 1;    }    fh=NULL;    fb=NULL;    n=0;    while (1) {        if (NULL==fgets(ln,256,af)) break;        L=strlen(ln);        if ('\n'==ln[L-1]) ln[L-1]=0;        printf("read %s\n",ln);        strcpy(fpn,"c:\\tmp\\");        strcat(fpn,ln);        ft=(struct FB *)malloc(sizeof(struct FB));        if (NULL==ft) {            printf("Can not malloc ft!\n");            fclose(af);            return 2;//之前的malloc在main退出后由操作系统自动free        }        printf("ft[%d]==%p\n",n,ft);        strcpy(ft->fn,fpn);        f=fopen(fpn,"rb");        if (NULL==f) {            printf("Can not open file %s!\n",fpn);            fclose(af);            return 3;//之前的malloc在main退出后由操作系统自动free        }        ft->fl=_filelength(fileno(f));        ft->b=malloc(ft->fl);        if (NULL==ft->b) {            printf("Can not malloc ft->b!\n");            fclose(f);            fclose(af);            return 4;//之前的malloc在main退出后由操作系统自动free        }        printf("ft[%d]->b==%p\n",n,ft->b);        if (ft->fl!=fread(ft->b,1,ft->fl,f)) {            printf("fread error!\n");            fclose(f);            fclose(af);            return 5;//之前的malloc在main退出后由操作系统自动free        }        fclose(f);        ft->next=NULL;        if (NULL==fh) {            ft->prev=NULL;            fh=ft;        } else {            fb->next=ft;            ft->prev=fb;        }        fb=ft;        n++;    }    fclose(af);    printf("-----list-----\n");    for (ft=fh;NULL!=ft;ft=ft->next) {        printf("%8d %s\n",ft->fl,ft->fn);        if (NULL!=ft) fb=ft;    }    printf("-----free-----\n");    n--;    if (NULL!=fh) {        for (ft=fb->prev;NULL!=ft;ft=ft->prev) {            if (NULL!=ft->next->b) {                printf("ft[%d]->b==%p\n",n,ft->next->b);                free(ft->next->b);            }            if (NULL!=ft->next) {                printf("ft[%d]==%p\n",n,ft->next);                free(ft->next);            }            n--;        }        if (NULL!=fh->b) {            printf("ft[0]->b==%p\n",fh->b);            free(fh->b);        }        printf("ft[0]==%p\n",fh);        free(fh);    }    return 0;}//C:\tmp\tmp\Debug>dir /a-d c:\tmp// 驱动器 C 中的卷是 C_HD5_1// 卷的序列号是 1817-D526//// c:\tmp 的目录////找不到文件////C:\tmp\tmp\Debug>tmp//找不到文件//-----list-----//-----free-----////C:\tmp\tmp\Debug>dir /a-d c:\tmp// 驱动器 C 中的卷是 C_HD5_1// 卷的序列号是 1817-D526//// c:\tmp 的目录////2011-06-30  18:04            44,840 my_c.rar//2011-06-30  17:18             1,036 err.frm//2011-06-30  14:32            14,243 出租.txt//2011-06-28  12:08            23,681 MSDN98书签.txt//             4 个文件         83,800 字节//             0 个目录 17,041,870,848 可用字节////C:\tmp\tmp\Debug>tmp//read my_c.rar//ft[0]==00421800//ft[0]->b==00520068//read err.frm//ft[1]==00421670//ft[1]->b==0052AFC0//read 出租.txt//ft[2]==00421530//ft[2]->b==00378F28//read MSDN98书签.txt//ft[3]==004213F0//ft[3]->b==0052B3F8//-----list-----// 44840 c:\tmp\my_c.rar//  1036 c:\tmp\err.frm// 14243 c:\tmp\出租.txt// 23681 c:\tmp\MSDN98书签.txt//-----free-----//ft[3]->b==0052B3F8//ft[3]==004213F0//ft[2]->b==00378F28//ft[2]==00421530//ft[1]->b==0052AFC0//ft[1]==00421670//ft[0]->b==00520068//ft[0]==00421800////C:\tmp\tmp\Debug> 
 
[解决办法]
C/C++ code
   while(phead->next)     {     p = phead->next;     phead = p; // phead 和 p 指向同一个东西     free(p); // free p后，phead不也free了      }