你能帮我解决这个问题吗？ [英] could you help me about this problem?

问题描述

#include" stdio.h"

#include" malloc.h"

struct student {

int age; < br $>
char * nms;

struct student * next;

};

struct student * create（）{

int ags = 0，size = sizeof（struct student）;

char * nms =" " ;;

struct student * head = NULL，* tail = NULL，* p = NULL;

scanf（"％d％s"& ags， NMS）; // -------------------这里!!!!!!

而（ags！= 0）{

p =（struct student *）malloc（size）;

nms =（char *）malloc（20）;

p-> age = ags;

p-> nms = nms;

p-> next = NULL;

if（head == NULL）{

head = p;

}否则{

tail-> next = p;

}

tail = p;

scanf（"％d％s"，& ags，nms）;

}

返回头部;

}

int main（无效）{

struct student * ptr = create（）;

while （ptr）{

printf（"％d ====％s \ n"，ptr-> age，ptr-> nms）;

free（ptr-> nms）;

free（ptr）;

ptr = ptr-> next;

}

}

************************************

i认为它没问题。但它不起作用！

为什么？

#include "stdio.h"
#include "malloc.h"
struct student{
int age;
char *nms;
struct student *next;
};
struct student *create(){
int ags=0,size=sizeof(struct student);
char *nms=" ";
struct student *head=NULL,*tail=NULL,*p=NULL;
scanf("%d%s",&ags,nms); //-------------------here!!!!!!
while(ags!=0){
p=(struct student * )malloc(size);
nms=(char *)malloc(20);
p->age=ags;
p->nms=nms;
p->next=NULL;
if(head==NULL){
head=p;
}else{
tail->next=p;
}
tail=p;
scanf("%d%s",&ags,nms);
}
return head;
}
int main(void) {
struct student *ptr=create();
while(ptr){
printf("%d====%s\n",ptr->age,ptr->nms);
free(ptr->nms);
free(ptr);
ptr=ptr->next;
}
}
************************************
i think that is no problem with it.but it doesn''t work!
why?

推荐答案

2月27日上午9:25，softwindow < softwin ... @ gmail.comwrote：

[...]

On Feb 27, 9:25 am, "softwindow" <[e-mail]:
[...]

free（ptr）;

ptr = ptr-> next;

}}


***************** *******************

i认为它没问题。但它不起作用！
$ b $为什么？

free(ptr);
ptr=ptr->next;
}}

************************************
i think that is no problem with it.but it doesn''t work!
why?

你没有给我们很多关于你认为不起作用的暗示。

的意思。但一个明显的问题是上面的代码。一旦你将

指针传递给free，你就不能尝试取消引用它。尝试一下

喜欢


tptr = ptr-> next;

free（ptr）;

ptr = tptr;


（当然还有适当的tptr声明。）


问候，

- = Dave

You didn''t give us much of a hint as to what you think "doesn''t work"
means. But one obvious problem is the code above. Once you pass a
pointer to free, you can''t then try to dereference it. Try something
like

tptr = ptr->next;
free(ptr);
ptr = tptr;

(with an appropriate declaration of tptr, of course.)

Regards,
-=Dave

2月27日，上午10:25，softwindow < softwin ... @ gmail.comwrote：

On Feb 27, 10:25 am, "softwindow" <[e-mail]:

#include" stdio.h"

#include" malloc.h" ;

struct student {

int age;

char * nms;

struct student * next;};


struct student * create（）{

int ags = 0，size = sizeof（struct student）;

char * NMS = QUOT; " ;;

struct student * head = NULL，* tail = NULL，* p = NULL;

scanf（"％d％s"& ags， NMS）; // -------------------这里!!!!!!

而（ags！= 0）{

p =（struct student *）malloc（size）;

nms =（char *）malloc（20）;

p-> age = ags;

p-> nms = nms;

p-> next = NULL;

if（head == NULL）{

head = p;

}否则{

tail-> next = p;

}

tail = p;

scanf（"％d％s"，& ags，nms）;

}

返回头部;}


int main（void）{

struct student * ptr = create（）;

while（ptr）{

printf（"％d ====％s \ n"，ptr-> age，ptr-> nms）;

free（ptr- > nms）;

免费（ptr）;

ptr = ptr-> next;

}}


********************************* ***

i认为它没问题。但它不起作用！

#include "stdio.h"
#include "malloc.h"
struct student{
int age;
char *nms;
struct student *next;};

struct student *create(){
int ags=0,size=sizeof(struct student);
char *nms=" ";
struct student *head=NULL,*tail=NULL,*p=NULL;
scanf("%d%s",&ags,nms); //-------------------here!!!!!!
while(ags!=0){
p=(struct student * )malloc(size);
nms=(char *)malloc(20);
p->age=ags;
p->nms=nms;
p->next=NULL;
if(head==NULL){
head=p;
}else{
tail->next=p;
}
tail=p;
scanf("%d%s",&ags,nms);
}
return head;}

int main(void) {
struct student *ptr=create();
while(ptr){
printf("%d====%s\n",ptr->age,ptr->nms);
free(ptr->nms);
free(ptr);
ptr=ptr->next;
}}

************************************
i think that is no problem with it.but it doesn''t work!

如果没有问题，那么为什么你说它不起作用。


对不起，我是不是心灵读者，你必须说出你的问题到底是什么。

If there is no problem, then why do you say it doesn''t work.

Sorry, I am not a mind reader, you will have to spell out what exactly
your issue is.

为什么？

why?

2月27日，上午10:25，softwindow < softwin ... @ gmail.comwrote：

On Feb 27, 10:25 am, "softwindow" <[e-mail]:

#include" stdio.h"

#include" malloc.h" ;

struct student {

int age;

char * nms;

struct student * next;};


struct student * create（）{

int ags = 0，size = sizeof（struct student）;

char * NMS = QUOT; " ;;

struct student * head = NULL，* tail = NULL，* p = NULL;

scanf（"％d％s"& ags， NMS）; // - - - - - - - - - -这里！！！！！！

#include "stdio.h"
#include "malloc.h"
struct student{
int age;
char *nms;
struct student *next;};

struct student *create(){
int ags=0,size=sizeof(struct student);
char *nms=" ";
struct student *head=NULL,*tail=NULL,*p=NULL;
scanf("%d%s",&ags,nms); //-------------------here!!!!!!

你的输入是什么，你有足够的内存分配给''nms''？

What is your input, do you have enough memory allocated for ''nms''?

while（ags！= 0）{

p =（struct student *）malloc（size）;

nms =（char *）malloc（20）;

p-> age = ags;

p-> nms = nms;

p-> next = NULL;

if（head == NULL）{

head = p;

} else {

tail-> next = p; < br $>
}

tail = p;

scanf（"％d％s"，& ags，nms）;

}

返回头;}


int main（void）{

struct student * ptr = create（） ;

while（ptr）{

printf（"％d ====％s \ n"，ptr-> age，ptr-> nms ）;

free（ptr-> nms）;

free（ptr）;

ptr = ptr-> next;

}}


************************************

i认为它没问题。但它不起作用！

为什么？

while(ags!=0){
p=(struct student * )malloc(size);
nms=(char *)malloc(20);
p->age=ags;
p->nms=nms;
p->next=NULL;
if(head==NULL){
head=p;
}else{
tail->next=p;
}
tail=p;
scanf("%d%s",&ags,nms);
}
return head;}

int main(void) {
struct student *ptr=create();
while(ptr){
printf("%d====%s\n",ptr->age,ptr->nms);
free(ptr->nms);
free(ptr);
ptr=ptr->next;
}}

************************************
i think that is no problem with it.but it doesn''t work!
why?

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