为什么我的代码不能编译？请帮忙！ [英] Why won't my code compile? Please help!

问题描述

好的..所以我需要一些C ++课程的帮助。我一直在网上使用教程来帮助我，但现在我只是被卡住了。我有以下代码：



server.h：

Okay.. so I need some help with my C++ class. I''ve been using tutorials online to help me, but now I''m just plain stuck. I have the following code:

server.h:

#ifndef USER_H
#define USER_H
#include <vector>
#include <iostream>
#include <string>
#include <my_global.h>
#include <mysql.h>
namespace Mainframe
{
class User
{

public:

	Mainframe::User::User(std::string);
	int grabInfo();
};
}
#endif

服务器。 cpp：

server.cpp:

#include "stdafx.h"
#include "server.h"

		MYSQL *conn;

    Mainframe::User::User(std::string id)
	{
	conn = mysql_init(NULL);

	//Connect to the server...
	mysql_real_connect(conn, "localhost", "root", "password", "users", 0, NULL, 0);
	}

	int Mainframe::User::grabInfo()
	{
		return mysql_query(conn, "SELECT * FROM users");
		mysql_close(conn);
	}

现在，您可能已经注意到，我正在使用MySQL C API进行数据库调用。这是我第一次使用它。无论如何，每次我尝试编译时都会收到错误：

Now, as you may have noticed, I am using MySQL C API for database calling. This is my first time using it. Anyway, every time I try to compile I get the error:

error C2512: no appropriate default constructor available

所以我做了一些研究并把它放在头文件中的构造函数之前：

So I did some research and put this before the constructor in my header file:

Mainframe::User::User();

然后我将引用的函数添加到我的cpp file：

I then added the referenced function to my cpp file:

Mainframe::User::User() { }

我编译。默认的构造函数错误消失了，但我只剩下这个了：

And I compile. The default constructor error is gone, but I''m instead left with this:

Error	5	error LNK2019: unresolved external symbol _mysql_real_connect@32 referenced in function "public: __thiscall Mainframe::User::User(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0User@Mainframe@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)	E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj)	MSQLClientTest


Error	8	error LNK2019: unresolved external symbol _mysql_query@8 referenced in function "public: int __thiscall Mainframe::User::grabInfo(void)" (?grabInfo@User@Mainframe@@QAEHXZ)	E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj)	MSQLClientTest

Error	6	error LNK2019: unresolved external symbol _mysql_init@4 referenced in function "public: __thiscall Mainframe::User::User(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0User@Mainframe@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)	E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj)	MSQLClientTest

Error	7	error LNK2019: unresolved external symbol _mysql_close@4 referenced in function "public: int __thiscall Mainframe::User::grabInfo(void)" (?grabInfo@User@Mainframe@@QAEHXZ)	E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj)	MSQLClientTest

Error	9	error LNK1120: 4 unresolved externals	1	E:\My Documents\Visual Studio 2010\Projects\LoveBird\Debug\MSQLClientTest.exe	1	MSQLClientTest

我不知道出了什么问题！请帮助我。我对C ++很陌生并原谅我，如果这样的话是一个愚蠢的问题。提前谢谢。

I have no idea what''s wrong! Please help me. I''m pretty new to C++ and forgive me if this is a stupid question. Thanks in advance.

推荐答案

basic_string @ DU？

basic_string@DU?

char_traits @ D @ std @@ V？

char_traits@D@std@@V?

allocator @ D @ 2 @@ std @@@ Z）E：\ My Documents\Visual Studio 2010 \\ \\ Project \ LoveBird \ MSQLClientTest \server.lib（connect.obj）MSQLClientTest


错误8错误LNK2019：未解析的外部符号_mysql_query @ 8在函数public：int __thiscall中引用Mainframe :: User :: grabInfo（void）（？grabInfo @ User @ Mainframe @@ QAEHXZ）E：\ My Documents\Visual Studio 2010 \Projects\LoveBird\MSQLClientTest\server.lib（connect。 obj）MSQLClientTest

错误6错误LNK2019：未解析的外部符号_mysql_init @ 4在函数public：__thiscall Mainframe :: User :: User中引用（类std :: basic_string< char，struct std :: char_traits< ; char>，类std :: allocator< char> >）（?? 0User @ Mainframe @@ QAE @ V？

allocator@D@2@@std@@@Z) E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj) MSQLClientTest Error 8 error LNK2019: unresolved external symbol _mysql_query@8 referenced in function "public: int __thiscall Mainframe::User::grabInfo(void)" (?grabInfo@User@Mainframe@@QAEHXZ) E:\My Documents\Visual Studio 2010\Projects\LoveBird\MSQLClientTest\server.lib(connect.obj) MSQLClientTest Error 6 error LNK2019: unresolved external symbol _mysql_init@4 referenced in function "public: __thiscall Mainframe::User::User(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0User@Mainframe@@QAE@V?

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