访问者问题 [英] Problem with Accessors

问题描述

这是我的代码。


main.cpp：


#include" cddb.h"


CDData * head;

CDData * curData;


int main（）{


head = new CDData（）;

curData = head;


EnterInfo（）;

Print（）;

返回0;

}


无效EnterInfo（）{

CDData * temp;

char * input = new char（）;

int ipInt;


system（" cls"）;


temp = new CDData（）;

curData-> SetNext（temp）;

curData = temp;


cout<< 请输入有关新CD的信息。\ nn;

cout<< " \ nAlbum name：" ;;

cin.getline（input，25）;

curData-> SetAlbumName（input）;

cout<< \艺术家姓名：" ;;

cin.getline（输入，25）;

curData-> SetArtistName（输入）;

cout<< " \ nYear发布：" ;;

cin>> ipInt;

curData-> SetYear（ipInt）;

}


void Print（）{

int i = 1;

curData = head;


while（true）{

curData = curData-> ; GetNext（）;

if（curData = NULL）

break;


cout<< CD＃ << i<< endl;

cout<< 专辑名称： << curData-> GetAlbumName（）<< endl;

cout<< 艺术家姓名： << curData-> GetArtistName（）<< endl;

cout<< 发布年份： << curData-> GetYear（）<< endl;

cout<< " ------------------------------------------- \\\
\ n" ;;


i ++;

}

}


cddb.h ：


#include< iostream>

#include< string>

using namespace std;


void EnterInfo（）;

void保存（）;

void Load（）;

void Print（） ;


class CDData {

private：

CDData * next; //对于链表

char * albumName;

char * artistName;

int year;

public：

//构造函数/析构函数

CDData（）{this-> SetNext（NULL）;}

~CDData（）{}

//访问者

char * GetAlbumName（）{return this-> albumName;}

char * GetArtistName（）{return this-> ; artistName;}

int GetYear（）{return year;}

CDData * GetNext（）{return next;}


void SetAlbumName（char * newName）{albumName = newName;}

void SetArtistName（char * newName）{artistName = newName;}

void SetYear（int newYear）{ year = newYear;}

void SetNext（CDData * newNext）{next = newNext;}

};


我'在打印功能运行期间出现访问冲突错误，当我试图使用GetXXX访问器时，
。


0x0041fc46处的未处理异常在CDDataBase.exe中：0xC0000005：访问

违规读取locati在0x00000004。


我做错了什么？

Here is my code.

main.cpp:

#include "cddb.h"

CDData* head;
CDData* curData;

int main(){

head = new CDData();
curData = head;

EnterInfo();
Print();
return 0;
}

void EnterInfo(){
CDData* temp;
char* input = new char();
int ipInt;

system("cls");

temp = new CDData();
curData->SetNext(temp);
curData = temp;

cout << "Please enter information about your new CD.\n";
cout << "\nAlbum name: ";
cin.getline(input, 25);
curData->SetAlbumName(input);
cout << "\nArtist name: ";
cin.getline(input, 25);
curData->SetArtistName(input);
cout << "\nYear Released: ";
cin >> ipInt;
curData->SetYear(ipInt);
}

void Print(){
int i = 1;
curData = head;

while(true){
curData = curData->GetNext();
if(curData = NULL)
break;

cout << "CD #" << i << endl;
cout << "Album Name: " << curData->GetAlbumName() << endl;
cout << "Artist Name: " << curData->GetArtistName() << endl;
cout << "Year Released: " << curData->GetYear() << endl;
cout << "-------------------------------------------\n\n";

i++;
}
}

cddb.h:

#include <iostream>
#include <string>
using namespace std;

void EnterInfo();
void Save();
void Load();
void Print();

class CDData {
private:
CDData *next; //For linked list
char* albumName;
char* artistName;
int year;
public:
//Constructor/Destructor
CDData(){ this->SetNext(NULL);}
~CDData(){}
//Accessors
char* GetAlbumName(){return this->albumName;}
char* GetArtistName(){return this->artistName;}
int GetYear(){return year;}
CDData* GetNext(){return next;}

void SetAlbumName(char* newName){albumName = newName;}
void SetArtistName(char* newName){artistName = newName;}
void SetYear(int newYear){year = newYear;}
void SetNext(CDData* newNext){next = newNext;}
};

I''m getting an access violation error during runtime at the print function,
when I''m trying to use the GetXXX accessors.

Unhandled exception at 0x0041fc46 in CDDataBase.exe: 0xC0000005: Access
violation reading location 0x00000004.

What am I doing wrong?

推荐答案

Jordan Tiona sade：

< snip>

Jordan Tiona sade:
<snip>

while（true）{
curData = curData-> GetNext（）;
if（curData = NULL）


if（curData == NULL）

break;

< snip>
我在访问期间遇到访问冲突错误打印功能的运行时，
当我试图使用GetXXX访问器时。

CDDataBase.exe中0x0041fc46处的未处理异常：0xC0000005：访问
违规读取位置0x00000004 。

我做错了什么？

while(true){
curData = curData->GetNext();
if(curData = NULL)
if(curData == NULL)
break;
<snip>
I''m getting an access violation error during runtime at the print function,
when I''m trying to use the GetXXX accessors.

Unhandled exception at 0x0041fc46 in CDDataBase.exe: 0xC0000005: Access
violation reading location 0x00000004.

What am I doing wrong?

TB

TB

Jordan Tiona写道：

Jordan Tiona wrote:

[..]
void Print（）{
int i = 1;
curData = head;

while（true ）{
curData = curData-> GetNext（）;
if（curData = NULL）


比较运算符是''==''，不是 =。在这里你只需要为''curData''指定NULL

。

休息;
[...]

[..]
void Print(){
int i = 1;
curData = head;

while(true){
curData = curData->GetNext();
if(curData = NULL)
Comparison operator is ''=='', not ''=''. Here you just assigned NULL
to ''curData''.
break;
[...]

V

V

Jordan Tiona写道：

Jordan Tiona wrote:

这是我的代码。

main.cpp：

#include" cddb.h"

CDData * head;
CDData * curData;

int main（）{< br =>
head = new CDData（）;
curData = head;

EnterInfo（）;
Print（）;
返回0;
}

void EnterInfo（）{
CDData * temp;
char * input = new char（）;
int ipInt;

system（cls）;

temp = new CDData（）;
curData-> SetNext（temp）;
curData = temp;

cout<< 请输入有关新CD的信息。\ n;;
cout<< " \ nAlbum name：" ;;
cin.getline（input，25）;
curData-> SetAlbumName（input）;
cout<< \艺术家姓名：" ;;
cin.getline（输入，25）;
curData-> SetArtistName（输入）;
cout<< \ nYear发布：" ;;
cin>> ipInt;
curData-> SetYear（ipInt）;
}

void Print（）{
int i = 1;
curData = head;

while（true）{
curData = curData-> GetNext（）;
if（curData = NULL）
break;

cout<< CD＃ << i<< endl;
cout<< 专辑名称： << curData-> GetAlbumName（）<< endl;
cout<< 艺术家姓名： << curData-> GetArtistName（）<< endl;
cout<< 发布年份： << curData-> GetYear（）<< endl;
cout<< " ------------------------------------------- \\\
\ n;

i ++;
}


cddb.h：

#include< iostream>
#include< string>
使用命名空间std;

void EnterInfo（）;
void Save（）;
void Load（）;
void Print（）;

class CDData {
private：
CDData * next; //对于链接列表
char * albumName;
char * artistName;
int year;
public：
//构造函数/析构函数
CDData（） {this-> SetNext（NULL）;}
~CDData（）{}
//访问者
char * GetAlbumName（）{return this-> albumName;}
char * GetArtistName（）{return this-> artistName;}
int GetYear（）{return year;}
CDData * GetNext（）{return next;}

void SetAlbumName（char * newName）{albumName = newName;}
void SetArtistName（char * newName）{artistName = newName;}
void SetYear（int newYear）{year = newYear;}
void SetNext（CDData * newNext）{next = newNext;}
};

我在打印功能运行期间遇到访问冲突错误，
当我''我试图使用GetXXX访问器。

CDDataBase.exe中0x0041fc46处理未处理的异常：0xC0000005：访问
违规读取位置0x00000004。

我做错了什么？

Here is my code.

main.cpp:

#include "cddb.h"

CDData* head;
CDData* curData;

int main(){

head = new CDData();
curData = head;

EnterInfo();
Print();
return 0;
}

void EnterInfo(){
CDData* temp;
char* input = new char();
int ipInt;

system("cls");

temp = new CDData();
curData->SetNext(temp);
curData = temp;

cout << "Please enter information about your new CD.\n";
cout << "\nAlbum name: ";
cin.getline(input, 25);
curData->SetAlbumName(input);
cout << "\nArtist name: ";
cin.getline(input, 25);
curData->SetArtistName(input);
cout << "\nYear Released: ";
cin >> ipInt;
curData->SetYear(ipInt);
}

void Print(){
int i = 1;
curData = head;

while(true){
curData = curData->GetNext();
if(curData = NULL)
break;

cout << "CD #" << i << endl;
cout << "Album Name: " << curData->GetAlbumName() << endl;
cout << "Artist Name: " << curData->GetArtistName() << endl;
cout << "Year Released: " << curData->GetYear() << endl;
cout << "-------------------------------------------\n\n";

i++;
}
}

cddb.h:

#include <iostream>
#include <string>
using namespace std;

void EnterInfo();
void Save();
void Load();
void Print();

class CDData {
private:
CDData *next; //For linked list
char* albumName;
char* artistName;
int year;
public:
//Constructor/Destructor
CDData(){ this->SetNext(NULL);}
~CDData(){}
//Accessors
char* GetAlbumName(){return this->albumName;}
char* GetArtistName(){return this->artistName;}
int GetYear(){return year;}
CDData* GetNext(){return next;}

void SetAlbumName(char* newName){albumName = newName;}
void SetArtistName(char* newName){artistName = newName;}
void SetYear(int newYear){year = newYear;}
void SetNext(CDData* newNext){next = newNext;}
};

I''m getting an access violation error during runtime at the print function,
when I''m trying to use the GetXXX accessors.

Unhandled exception at 0x0041fc46 in CDDataBase.exe: 0xC0000005: Access
violation reading location 0x00000004.

What am I doing wrong?

CDData :: albumName a nd CCData :: artistName永远不会被初始化。

如果你坚持使用char *，你必须实现复制构造函数，

赋值运算符和析构函数。


如果使用std :: string而不是

char *，大多数问题都会解决。

提示：如果你想要一个25个字符的缓冲区使用

char * buf = new char [25];

并且不要忘记稍后删除它

delete [] buf;


为什么宣布

+ void EnterInfo（）;

+ void Save（）;

+ void Load（）;

+ void Print（）;
如果在main.cpp中实现了cddb.h中的
。

你真的希望每个使用CDData

的应用程序都必须提供它们吗？


问候，Stephan
br **** @ osb-systems.com

通信网络的开源评级和计费引擎。

CDData::albumName and CCData::artistName are never initialized.
If you stick with char*, you must implement the copy constructor,
assignment operator and destructor.

Most of your problems will solve if you use std::string instead of
char*.
Hint: if you want a buffer of 25 characters use
char* buf = new char[25];
and don''t forget to delete it later
delete [] buf;

Why do you declare
+ void EnterInfo();
+ void Save();
+ void Load();
+ void Print();
in cddb.h if there are implemented in main.cpp.
Do you really want that every application that uses CDData
has to provide them?

Regards, Stephan
br****@osb-systems.com
Open source rating and billing engine for communication networks.

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