Question

I’m getting values from mysql database, I want to organize it with each row returned. here’s my struct(example only):

typedef struct 
{
    char* name;
    char* etc;
    int state;

} person; 

and the MySql:

MYSQL * con;
mysql_connect(&con); //connect to mysql database and set handle to con variable.
MYSQL_ROW row;
MYSQL_RES * result;
int num_fields, i;
mysql_query(con, "select name,etc,state from db.tbl");
result = mysql_store_result (con);
num_fields = mysql_num_fields (result);
person tempdata;
person personlist[num_fields * sizeof(person)]; //the size if the problem, I believe... 
while((row = mysql_fetch_row (result))) {
   tempdata.name = row[0];
   tempdata.etc  = row[1];
   tenpdata.state = atoi(row[2]);
   personlist[i++] = tempdata;  // the error line
}

mysql_free_result (result);
mysql_close (con);

but it returns Segmentation fault how to fix this? thanks in advance.

Answer 1

When you declare an array of structures, you specify its size as number of elements. Number of persons in your case. Declare it without sizeof(person): person personlist[num_fields];.

You also use variable i without being initialized. Change its declaration to int num_fields, i = 0;.

And note that tempdata.name = row[0]; makes name point to the same data as row[0] points to. You probably want to allocate memory for name and copy row[0] into it (check unwinds answer).