C MySQL Types Error - mysql

Question

I'm trying to store results taken from a MySQL query into an array of structs. I can't seem to get the types to work though, and I've found the MySQL documentation difficult to sort through.
My struct is:
struct login_session
{
char* user[10];
time_t time;
int length;
};
And the loop where I'm trying to get the data is:
while ( (row = mysql_fetch_row(res)) != NULL ) {
strcpy(records[cnt].user, &row[0]);
cnt++;
}
No matter what I try though I constantly get the error:
test.c:45: warning: passing argument 1 of ‘strcpy’ from incompatible pointer type
/usr/include/string.h:128: note: expected ‘char * __restrict__’ but argument is of type ‘char **’
test.c:45: warning: passing argument 2 of ‘strcpy’ from incompatible pointer type
/usr/include/string.h:128: note: expected ‘const char * __restrict__’ but argument is of type ‘MYSQL_ROW’
Any pointers?

Answer 1

Multiple problems, all related to pointers and arrays, I recommend you do some reading.
First, char * user[10] is defining an array of 10 char * values, not an array of char, which is was I suspect you want. The warning even says as much, strcpy() expects a char *, the user field on its own is seen as a char **.
Second, you're one & away from what you want in the second argument.
Copied from mysql.h header:
typedef char **MYSQL_ROW; /* return data as array of strings */
A MYSQL_ROW is an array of char arrays. Using [] does a dereference, so you dereference down to a char * which is what strcpy() takes, but then you take the address of it using &.
Your code should look more like this:
struct login_session
{
char user[10];
time_t time;
int length;
};
while ( (row = mysql_fetch_row(res)) != NULL ) {
strcpy(records[cnt].user, row[0]);
cnt++;
}
I don't know what guarantees you have about the data coming from mysql, but if you can't be absolutely sure that the rows are <= 10 characters long and null ('\0') terminated, you should use strncpy() to avoid any possibility of overflowing the user array.