C/C++程序中如何連接MySQL數(shù)據(jù)庫？

feeling

mysql_init后，我用mysql_real_connect連接MySQL數(shù)據(jù)庫，出錯(cuò)，提示如下：
Failed to connect to database : Can't connect to local MySQL server through socket '/tmp/mysql.sock' (146)
由于MySQL數(shù)據(jù)庫是另一個(gè)用戶mysql啟動(dòng)的，我就su到mysql用戶下執(zhí)行測(cè)試程序，出錯(cuò)，提示：
Failed to connect to database : Access denied for user 'mysql'@'localhost' (using password: NO)
奇怪，于是，我在程序代碼中加上了用戶口令信息，再次出錯(cuò)，提示如下：
Failed to connect to database : Client does not support authentication protocol requested by server; consider upgrading MySQL client

何解？