Paul,
your suggestion was right. My program works now. Thank you very much!
Yury
On Mon, 17 May 1999, Paul DuBois wrote:
> At 6:42 PM -0700 5/17/1999, Yury Bukhman wrote:
> >I am trying to create a simple MySQL client program in C. I'm getting a
> >runtime "segmentation fault" error. I could not figure out why. Please,
> >help!
> >
> >____
> >Here is gdb diagnostic:
> >(command: gdb programname core)
> >Program terminated with signal 11, Segmentation fault.
> >find_solib: Can't read pathname for load map: Input/output error
> >
> >#0 0x8049f4d in mysql_real_connect ()
> >
> >____
> >Here is the relevant part of my program:
> >
> >#include <stdio.h>
> >#include "mysql.h"
> >
> >int main(){
> > MYSQL *mysql; /*server handle*/
> > char *host = "localhost"; /*hostname or an IP address*/
> > char *user = "guest"; /*user ID*/
> > char *passwd = NULL; /*password*/
> > char *db = "dom_base"; /*database name*/
> > unsigned int port = 0; /*TCP-IP port*/
> > char *unix_socket = "/tmp/mysql.sock"; /*UNIX socket for mysql
> >connection*/
> > unsigned int client_flag = 0;
> > char *query;
> > MYSQL_RES *result;
> > MYSQL_ROW row;
> >
> > char *id, *method; /*pdb table field values*/
> > float resoln, r; /*pdb table field values*/
> >
> >
> > if(mysql_init(mysql)==NULL){ /*initialize server handle*/
> > printf("mysql_init failed\n");
> > return 1;
> > }
> > if(mysql_real_connect(mysql, host, user, passwd, db, port,
> > unix_socket, client_flag)==NULL){
> >(at this statement, program crushes)
>
>
>
> Not surprising! You're passing a pointer to a MYSQL structure to
> mysql_init() that doesn't point to anything useful. You're supposed
> to pass a pointer to an already-allocated structure.
>
> Try changing this:
>
> MYSQL *mysql;
>
> to this:
>
> MYSQL mysql_struct, *mysql = &mysql_struct;
>
>
> Another way of doing this would be to let mysql_init() allocate
> the structure for you by passing NULL. But then you need to save
> the return value. You could do this like so:
>
> MYSQL *mysql;
>
> ...
>
> if((mysql = mysql_init(mysql))==NULL){ /*initialize server handle*/
> printf("mysql_init failed\n");
> return 1;
> }
>
> ...
>
> --
> Paul DuBois, paul@stripped
> Northern League Chronicles: http://www.snake.net/nl/
>
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