From: walter harms
Date: May 7 2009 1:10pm
Subject: Re: Memory corrupting, while retrive the query generated
List-Archive: http://lists.mysql.com/mysql/217443
Message-Id: <4A02DDB0.7010902@bfs.de>
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hi ravi,

this works for me. it should help
you to get a starting point



re,
 wh


/*
  simpple DB connect test
  gcc  -L/usr/lib/mysql -lmysqlclient connect.c
*/

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>

int main()
{
	MYSQL *MySQL;
	MYSQL_ROW row;
	MYSQL_RES *res;
	char *dbhost = "localhost";
	char *dbuser = "dbuser";
	char *dbpass = "";
	char *dbname = "mysql";
	char *sel_smt;
	int ret;

	MySQL = mysql_init(NULL);
	if (MySQL == NULL) {
		fprintf(stderr, "Connection failed\n");
		exit(1);
	}


	if (mysql_real_connect
	    (MySQL, dbhost, dbuser, dbpass, dbname, 0, NULL, 0) < 0) {

		fprintf(stderr, "%s\n", mysql_error(MySQL));
		exit(1);
	}


	asprintf(&sel_smt, "select count(*) from user");


	if (mysql_query(MySQL, sel_smt) != 0) {

		fprintf(stderr, "%s\n", mysql_error(MySQL));
		exit(1);
	}


	res = mysql_store_result(MySQL);
	if (res == NULL) {

		fprintf(stderr, "%s\n", mysql_error(MySQL));
		exit(1);
	}

	row = mysql_fetch_row(res);

	printf("%s\n", row[0] ? row[0] : "NULL");

	free(sel_smt);
	mysql_free_result(res);

	mysql_close(MySQL);
	exit(0);
}



Ravi raj schrieb:
> Dear All,
> 
>             I want to connect MYSQL with following C application , while i'm trying to retrive the query generated , its corrupting the memory. 
> 
>      Is there any solution , to retrive the query generated with out any memory crashes?
> 
>      Please help me to solve this problem.
> 
> code as follows,
> 
> -------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
>   1.. #include <stdio.h>
>   2.. #include <stdlib.h>
>   3.. #include <string.h>
>   4.. #include "mysql.h"
>   5.. ?
>   6.. int main()
>   7.. {
>   8.. MYSQL *conn;
>   9.. MYSQL_RES *res;
>   10.. MYSQL_ROW row;
>   11.. MYSQL_FIELD *field;
>   12.. unsigned int i = 0;
>   13.. char table_type[30];
>   14.. char buffer[200];
>   15.. unsigned int num_fields;
>   16.. char *server = "localhost";
>   17.. char *user = "root";
>   18.. char *password = ""; /* set me first */
>   19.. char *database = "test";
>   20.. conn = mysql_init(NULL);
>   21.. ?
>   22.. /* Connect to database */
>   23.. if (!mysql_real_connect(conn, server, user, password, database, 0, NULL, 0))
>   24.. {
>   25.. fprintf(stderr, "%s\n", mysql_error(conn));
>   26.. exit(1);
>   27.. }
>   28.. ?
>   29.. if(mysql_ping(conn))
>   30.. {
>   31.. printf("error in connection \n");
>   32.. exit(1);
>   33.. }
>   34.. sprintf(table_type, "method");
>   35.. ?
>   36.. sprintf(buffer, "select mid, mname from %s;", table_type);
>   37.. mysql_query(conn, buffer);
>   38.. res = mysql_store_result(conn);
>   39.. num_fields = mysql_num_fields(res);
>   40.. 
>   41.. while ((row = mysql_fetch_row(res)) != NULL)
>   42.. {
>   43.. for(i = 0;i < num_fields;i++)                                   //here is the problem , num_fields is corrupting 
>   44.. printf("%s\n", row[i]?row[i]:"NULL");
>   45.. }
>   46.. mysql_free_result(res);
>   47.. mysql_close(conn);
>   48.. return 0;
>   49.. }
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
> 
> Regards, 
> Raviraj
> -----------------------------------------
> mobile : (91) (0) 9742293013
> www.vinjey.com
> P Think before you print
> /* work should be challenging 
> and the challenge should be fun */