/*****************

connect.cpp

g++ connect.cpp -o connect -I /usr/include/mysql/ -L /usr/lib/mysql/ -lmysqlclient

****************/#include#include#include#include"mysql.h"

classCMysqlInterface

{public:

CMysqlInterface();~CMysqlInterface();voidmysqlLibInit();voidmysqlLibDestroy();intConnect();intClose();private:

MYSQL*m_mysqlPtr;

};intmain()

{

printf("version 1.1\n");int iRet = -1;

CMysqlInterface MysqlObj;

iRet=MysqlObj.Connect();if(0 ==iRet)

{

printf("mysql_real_connect success\n");

}else{

printf("mysql_real_connect failed\n");

}return 0;

}

CMysqlInterface::CMysqlInterface()

{

printf("CMysqlInterface\n");

m_mysqlPtr=NULL;

m_mysqlPtr=mysql_init(NULL);

}

CMysqlInterface::~CMysqlInterface()

{

Close();

}intCMysqlInterface::Close()

{int iRet = 0;if(NULL !=m_mysqlPtr)

{

mysql_close(m_mysqlPtr);

m_mysqlPtr=NULL;

}returniRet;

}voidCMysqlInterface::mysqlLibDestroy()

{

mysql_library_end();

}intCMysqlInterface::Connect()

{

printf("Connect\n");int iRet = -1;

m_mysqlPtr= mysql_real_connect(m_mysqlPtr,"localhost","root","csql","child",0,NULL,0);if(m_mysqlPtr)

{

iRet= 0;

}returniRet;

}

exbot@ubuntu:~/wangqinghe/MySql/20190621/01$ g++ connect.cpp -o connect -I /usr/include/mysql/ -L /usr/lib/mysql/ -Imysqlclient

/tmp/cceJyiND.o：在函数‘CMysqlInterface::CMysqlInterface()’中：

connect.cpp:(.text+0xaf)：对‘mysql_init’未定义的引用

/tmp/cceJyiND.o：在函数‘CMysqlInterface::Close()’中：

connect.cpp:(.text+0x100)：对‘mysql_close’未定义的引用

/tmp/cceJyiND.o：在函数‘CMysqlInterface::mysqlLibDestroy()’中：

connect.cpp:(.text+0x121)：对‘mysql_server_end’未定义的引用

/tmp/cceJyiND.o：在函数‘CMysqlInterface::Connect()’中：

connect.cpp:(.text+0x17c)：对‘mysql_real_connect’未定义的引用

collect2: error: ld returned 1 exit status

这个问题是因为连接命令出了错误 后面跟的应该是 -l 而不是-L

输出结果：

exbot@ubuntu:~/wangqinghe/MySql/20190621/02$ g++ connect.cpp -o connect -I /usr/include/mysql/ -L /usr/lib/mysql/ -lmysqlclient

exbot@ubuntu:~/wangqinghe/MySql/20190621/02$ ./connect

version 1.1

CMysqlInterface

Connect

mysql_real_connect success