User can connect through PDO but not through C mysql_real_connect - mysql

Question

I manage a MySQL database on my local machine and connect to it through C by running the following program:
#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>
int main(int argc, char** argv ) {
my_init();
printf("MySQL client version: %s\n", mysql_get_client_info());
MYSQL mysql;
printf( "%p\n", &mysql );
MYSQL* mysql_initiate = mysql_init(&mysql);
printf( "%p\n", mysql_initiate );
MYSQL* attempt = mysql_real_connect(&mysql, "localhost","User","********","DB",0,NULL,0);
printf( "%p\n", attempt );
if(attempt != NULL) {
printf("OK\n");
}
else {
printf("Error: %s\n", mysql_error(&mysql));
}
mysql_close(&mysql);
return 0;
}
It is compiled by the following commands:
gcc -c `mysql_config --cflags` main.c
gcc -o a.run main.o `mysql_config --libs`
Where mysql_config --cflags outputs
-I/usr/include/mysql -DBIG_JOINS=1 -fno-strict-aliasing -g -DNDEBUG
and mysql_config --libs outputs
-L/usr/lib/x86_64-linux-gnu -lmysqlclient -lpthread -lz -lm -ldl
The program compiles fine, but when executed, it outputs:
MySQL client version: 5.5.50
0x7fffcb8403e0
0x7fffcb8403e0
(nil)
Error: Access denied for user 'User'#'localhost' (using password: YES)
The user's name, password and database name have been changed for this present thread.
PHP connects successfully with the actual triplet of names and password, thus the credentials on User are not the cause of the problem. I made a plain copy-paste from the PHP code to the C code, there is no inaccuracy in the strings.
The same problem occurs when:
trying connecting as root,
trying with having granted all the possible privileges for User,
trying with a test user, granted all privileges with a one-letter password,
having changed the variables mysql and mysql_initiate into blip and blop (if some miraculous undetected collision would have occurred).
The Apache server is launched when I ran the executable, to testify I could connect to phpmyadmin. I tried after I logged out from phpmyadmin, same problem. The same problem occurs when I put NULL instead of "localhost", when I put the port 3306 (it is the MySQL port, told by netstat -natp) instead of 0.
Why could User connect to the database through PHP and why can't he connect to it through C?
I have googled the problem but there is nothing on the topic.
The version of gcc is
gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
I am running under Linux Mint 17 Qiana.
MySQL is managed through XAMPP 7.0.6-0 and the database through phpmyadmin with the following versions and configurations (data retrieved from phpmyadmin welcome page):
Database server:
Server: Localhost via UNIX socket
Server type: MariaDB
Server version: 10.1.13-MariaDB - Source distribution
Protocol version: 10
User: root#localhost
Server charset: UTF-8 Unicode (utf8)
Web server:
Apache/2.4.18 (Unix) OpenSSL/1.0.2h PHP/7.0.6 mod_perl/2.0.8-dev Perl/v5.16.3
Database client version: libmysql - mysqlnd 5.0.12-dev - 20150407
PHP extension: mysqli
PHP version: 7.0.6
I am stuck facing a wall, any help appreciated.
If you need some extra info, feel free to ask.
Thanks in advance.

Answer 1

Beforehand I have browsed about similar problems and understood that some other users have solved their problems by removing XAMPP. I didn't know it was also my case. I wanted to try other things before resorting to such end.
I read that some XAMPP scripts about setting/changing the root password is deprecated.
I have gotten rid of XAMPP. XAMPP somehow corrupts the MySQL database when it comes to MySQL users and their rights.
In addition I have uninstalled mysql, apache and so on, then reinstalled them "by hand". It works.
I only now came accross that page:
https://community.apachefriends.org/f/viewtopic.php?f=16&t=72519
Maybe it would have solved my problem, maybe not. Anyway, I don't advise using XAMPP anymore.