从我的程序连接到mysql网络数据库

我试图从我的程序连接到mysql web数据库，但我一直得到：

Can't connect to MySQL server on 'mysql7.000webhost.com' (51) 

我正在使用这个网站免费的mysql服务器：

000webhost.com

这是我的代码或我在谷歌上找到的开始学习的代码。

#include <mysql.h>
#include <stdio.h>
#include <stdlib.h>
// just going to input the general details and not the port numbers
struct connection_details
{
    char *server;
    char *user;
    char *password;
    char *database;
};
MYSQL* mysql_connection_setup(struct connection_details mysql_details)
{
    // first of all create a mysql instance and initialize the variables within
    MYSQL *connection = mysql_init(NULL);
    // connect to the database with the details attached.
    if (!mysql_real_connect(connection,mysql_details.server, mysql_details.user, mysql_details.password, mysql_details.database, 0, NULL, 0)) {
        printf("Conection error : %sn", mysql_error(connection));
        exit(1);
    }
    return connection;
}
MYSQL_RES* mysql_perform_query(MYSQL *connection, char *sql_query)
{
    // send the query to the database
    if (mysql_query(connection, sql_query))
    {
        printf("MySQL query error : %sn", mysql_error(connection));
        exit(1);
    }
    return mysql_use_result(connection);
}
int main()
{
    MYSQL *conn;        // the connection
    MYSQL_RES *res; // the results
    MYSQL_ROW row;  // the results row (line by line)
    struct connection_details mysqlD;
    mysqlD.server = (char*)"mysql7.000webhost.com";  // where the mysql database is
    mysqlD.user =  (char*)"a1206305_test";      // the root user of mysql   
    mysqlD.password =  (char*)"testthis1"; // the password of the root user in mysql
    mysqlD.database =  (char*)"a1206305_test";  // the databse to pick
    // connect to the mysql database
    conn = mysql_connection_setup(mysqlD);
    // assign the results return to the MYSQL_RES pointer
    res = mysql_perform_query(conn, (char*) "show tables");
    printf("MySQL Tables in mysql database:n");
    while ((row = mysql_fetch_row(res)) !=NULL)
        printf("%sn", row[0]);
    /* clean up the database result set */
    mysql_free_result(res);
    /* clean up the database link */
    mysql_close(conn);
    return 0;
}

为什么它不连接？