请教关于用c连接mysql数据库的问题

cavider

#include <stdio.h>;
#include <mysql.h>;

#define def_host_name NULL
#define def_user_name NULL
#define def_password NULL
#define def_db_name NULL

MYSQL *regulation;

int
main (int argc,char *argv[])
{

regulation = mysql_init (NULL);
if (regulation == NULL)
{
fprintf (stderr,"mysql_init() failed (probbly out of memory)\n";
exit (1);
}
if (mysql_real_connect (
regulation,
def_host_name,
def_user_name,
def_password,
def_db_name,
0,
NULL,
0)
== NULL)

{
fprintf (stderr,"mysql_real_connect() failed:\nError %u (%s)\n",
mysql_errno (regulation), mysql_error (regulation));
exit (1);
}
mysql_close (regulation);
exit (0);
}

这段代码执行后应会有什么结果???(我执行后没有什么反应)
编译时没有报错
我用的编译指令:
gcc -I/usr/include/mysql -L/usr/lib/mysql -lmysqlclient test2.c
能解释一下各参数的意义吗???(尤其是最后一个(test2.c不算))

cavider

help