10 messages in com.mysql.lists.mysqlRe: c program Bus Error (core dumped)
FromSent OnAttachments
Andy Ford11 Jan 2005 05:05 
Andy Ford11 Jan 2005 05:13 
Jose Miguel Pérez11 Jan 2005 05:57 
Andy Ford11 Jan 2005 06:18 
Andy Ford11 Jan 2005 07:29 
Jose Miguel Pérez11 Jan 2005 07:52 
Andy Ford11 Jan 2005 08:10 
Andy Ford11 Jan 2005 08:25 
Jose Miguel Pérez11 Jan 2005 08:46 
Andy Ford11 Jan 2005 09:32 
Subject:Re: c program Bus Error (core dumped)
From:Andy Ford (andy@telindus.co.uk)
Date:01/11/2005 06:18:54 AM
List:com.mysql.lists.mysql

Thanks Jose ...

but I still get the Bus Error message with the following code...

int main(char **args) { MYSQL_RES *result; MYSQL_ROW row; MYSQL *connection, mysql; int state; int PORTNUM = 3306;

mysql_init(&mysql); connection = mysql_real_connect(&mysql, "localhost", "root", "0sg0sb4Ig", "oui", PORTNUM, NULL, 0);

if( connection == NULL ) { printf("%s\n",mysql_error(&mysql)); return 1; } else { printf("%s\n","Everything Cool with the connection"); } state = mysql_query(connection, "SELECT sysName from inv_device"); result = mysql_store_result(connection); if (result) { printf( "Return set: columns=%d, rows=%d \n", mysql_field_count(connection), mysql_num_rows(result)); mysql_free_result(result); } else { printf("%s\n", mysql_error(connection)); return 1; } mysql_close(connection); printf("%s\n","Done."); }

Regards

Andy

On Tue, 2005-01-11 at 14:57 +0100, Jose Miguel Pérez wrote:

Hi Andy,

state = mysql_query(connection, "SELECT * from mytable"); ******* ^^^^^^ if( state ) { printf(mysql_error(connection)); return 1; } else { printf("Everything Cool with the query\n"); }

// New code, retrieve resultset. -------- result = mysql_store_result(connection); if (result) { printf( "Return set: columns=%d, rows=%d \n", mysql_field_count(connection), mysql_num_rows(result)); mysql_free_result(__result); } else { printf("%s\n", mysql_error(connection)); return 1; } // New code -----------------------------

mysql_close(connection); printf("Done.\n");

After doing a SELECT statement you should issue a "mysql_store_result" / "mysql_use_result" operation to flush the resultset returned (even an empty resultset). In fact, you should flush the resultset stream with every SQL statement that returns data like SELECT, SHOW, DESCRIBE, and the like. See the manual page on "mysql_store_result" for more information. Once in there, you can follow the directions about section "21.2.3.20 mysql_field_count()" about using "mysql_field_count" to check in you need to flush the resultset. Do not forget to call "mysql_free_result" to free the memory allocated for the returned resultset.

Hope this helps, maybe mysql_close(...) got confused by pending data from the server.

One note though, you should NEVER use 'printf(whatever);' use 'printf("%s", whatever);' instead. If it happends to be some "%" inside "whatever" you will get coredumps. For instance, see what happends when in your program, mysql_error(connection) returns "Please use %d to display integers." (Not a real MySQL error, obviously!! :-)

Cheers, Jose Miguel.

-- perl -e "print qq^bIG VeRN ! ^^qq^#'#Yv#=<D+ ^"

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