C MySql

chymeira · 03-28-2011, 09:30 PM

Hello everyone,

Im trying to write a program that interacts with MySql in C . Im using slackware 13.1 64 bit and Ive installed MySql , getting help from this page : http://www.basicconfig.com/linuxserv...ysql_slackware .

This is the program I have ( I know they arent any vars here , i just thought it wasnt necessary )

Code:

#include <stdio.h>
#include <mysql/my_global.h>
#include <mysql/my_sys.h>
#include <mysql/mysql.h>

int main(int argc, char** argv)
{
  MY_INIT(argv[0]);

  if(mysql_library_init(0, NULL, NULL))  {
    fprintf(stderr, "mysql_library_init() failed\n");
    exit(1);
  }

  conn = mysql_init(NULL);
  if(conn == NULL) {
    fprintf(stderr, "mysql_init() failed ( probably out of memory)\n");
    exit(1);
  }

  if(mysql_real_connect(conn, opt_host_name, opt_user_name, opt_password,
			opt_db_name, opt_port_num, opt_socket_name,
			opt_flags) == NULL) {
    fprintf(stderr, "mysql_real_connect() failed\n");
    mysql_close(conn);
    exit(1);
  }

  mysql_close(conn);
  mysql_library_end();
  exit(0);
}

This program is from the MySql website ( a tutorial they have up there ). When I run this program I get hundreds of lines of errors , nothing related to my program , but the headers, indicating that there are syntax errors and all kinds of other problems in them. So I was wondering if you could help me out with my problem .

Thanks in advance.

nigerag · 03-28-2011, 10:08 PM

Look at the mysqld log file and see if it gives you any clue.

dwhitney67 · 03-28-2011, 10:20 PM

Quote:

Originally Posted by chymeira

When I run this program I get hundreds of lines of errors , nothing related to my program , but the headers, indicating that there are syntax errors and all kinds of other problems in them.

Syntax errors? These come when you compile the program; you may also get link errors when you attempt to build the executable. Yet above you claim you get these when you "run this program". Please elaborate a little further, because your statement makes no sense.

Please provide the GCC statement you use to compile (and link) the program. Also it would be helpful to provide the complete source listing, not just what you think is relevant.

chymeira · 03-28-2011, 10:24 PM

I mean when I compile , srry about that ..

This is the gcc statement :
gcc -g -o connect connect.c -lmysqlclient -lz

This is how the tutorial told me to do it , like I said I just started an hour ago.
Here are some of the errors I get ( this is like 15% )

Quote:

/usr/include/mysql/my_global.h:80:23: error: my_config.h: No such file or directory
/usr/include/mysql/my_global.h:615:26: error: my_attribute.h: No such file or directory
/usr/include/mysql/my_global.h:651:21: error: my_dbug.h: No such file or directory
In file included from connect1.c:2:
/usr/include/mysql/my_global.h:690: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'size_socket'
/usr/include/mysql/my_global.h:815:2: error: #error "please add -DSTACK_DIRECTION=1 or -1 to your CPPFLAGS"
/usr/include/mysql/my_global.h:1000:2: error: #error Neither int or long is of 4 bytes width
/usr/include/mysql/my_global.h:1070: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'os_off_t'
/usr/include/mysql/my_global.h:1569: error: static declaration of 'rint' follows non-static declaration
/usr/include/mysql/my_global.h: In function 'rint':
/usr/include/mysql/my_global.h:1579: error: 'DBL_MANT_DIG' undeclared (first use in this function)
/usr/include/mysql/my_global.h:1579: error: (Each undeclared identifier is reported only once
/usr/include/mysql/my_global.h:1579: error: for each function it appears in.)
In file included from connect1.c:3:
/usr/include/mysql/my_sys.h:34:63: error: m_ctype.h: No such file or directory
/usr/include/mysql/my_sys.h:36:21: error: typelib.h: No such file or directory
In file included from connect1.c:3:
/usr/include/mysql/my_sys.h: At top level:
/usr/include/mysql/my_sys.h:227: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'my_thread_stack_size'
/usr/include/mysql/my_sys.h:235: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token
/usr/include/mysql/my_sys.h:236: error: expected '=', ',', ';', 'asm' or '__attribute__' before '*' token
/usr/include/mysql/my_sys.h:237: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'compiled_charsets'
/usr/include/mysql/my_sys.h:240: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'my_file_opened'

The problem is I have all those files ( my_config.h .... etc )

Thank you

nigerag · 03-29-2011, 12:36 AM

Your compiler can not find the header files. Make sure you install the mysql source. In my case (I'm running Fedora) I had to install mysql-devel package.

nigerag · 03-29-2011, 12:39 AM

My apologies. I've just noticed you mentioned you had these files.

dwhitney67 · 03-29-2011, 03:59 AM

Chymeira,

I'm almost certain that there is something wrong with the installation of your MySQL development package. I have this package (perhaps a meta-package) installed on my Ubuntu 10.04 system, and I had no trouble compiling/linking the following program (note, it is not important that it wont run successfully; the point it to compile it):

Code:

#include <mysql/mysql.h>

#include <stddef.h>   /* for NULL */

int main(void)
{
   MYSQL* conn = NULL;

   char hostname[20];
   char username[20];
   char password[20];
   char database[20];
   char socketname[20];
   unsigned int  port = 9000;
   unsigned long flag = 0;

   mysql_library_init(0, NULL, NULL);

   conn = mysql_init(NULL);

   mysql_real_connect(conn, hostname, username, password, database, port, socketname, flag);

   mysql_close(conn);
   mysql_library_end();

   return 0;
}

To build:

Code:

gcc -Wall mysql.c -lmysqlclient

I would recommend that you re-verify the installation of the MySQL development package. Did you use your system's package manager to install it, or did you install it manually from a tar-ball containing the source code?

EDIT:

Doh! It turns out the errors are from including the following header files:

Code:

#include <mysql/my_global.h>
#include <mysql/my_sys.h>

I guess the moral of the story is to not include them, if they are unnecessary. The other alternative, and probably the best solution, is to always compile with the path to the MySQL header files specified:

Code:

gcc -Wall -I/usr/include/mysql mysql.c -lmysqlclient

chymeira · 03-29-2011, 10:40 AM

Thank you very much for all your replies .
What I did is compile like the following ( ty for that dwhitney ) :

gcc -Wall -I /usr/include/mysql connect1.c -o connect1 -lmysqlclient

and it works fine now.

dwhitney67 · 03-29-2011, 11:09 AM

It should be noted that by using the -I option, you no longer are required to specify the header files using their respective directory; for example, the following should be sufficient when using -I/usr/include/mysql:

Code:

#include <mysql.h>

...