MySQL database connection Function Memory leakage solution

Write a test program when using C in Linux to operate MySQL database

1. IntMain (Void)
2. {
3. MYSQL m_mysql;
4. Mysql_init (& m_mysql );
6. Const CharPLocalhost [] ="Localhost";
7. Const CharPUser [] ="Root";
8. Const CharPPass [] ="123456";
9. Const CharPDB [] ="HTTPCONTROL";
11. If(Mysql_real_connect (& m_mysql, pLocalhost, pUser, pPass, pDB, 0, NULL, 0) = NULL)
    
12. // Mysql_connect () connects to a MySQL server. This function is not recommended.mysql_real_connect().
    
13. Cout <"Connect failed"<Endl;
14. Else
15. Cout <"Connect success"<Endl;
17. Mysql_close (& m_mysql );
18. Return0;
19. }

Use valgrind to detect memory leakage after compilation

[Root @ localhost string] # valgrind -- tool = memcheck -- leak-check = full./mysql
==10352 = Memcheck, a memory error detector
= 10352 = Copyright (C) 2002-2009, and gnu gpl 'd, by Julian Seward et al.
= 10352 = Using Valgrind-3.5.0 and LibVEX; rerun with-h for copyright info
==10352 = Command:./mysql
= 10352 =
Connect success
= 10352 =
==10352 === heap summary:
= 10352 = in use at exit: 61,336 bytes in 16 blocks
= 10352 = total heap usage: 118 allocs, 102 frees, 115,929 bytes allocated
= 10352 =
= 10352 = 24,528 bytes in 6 blocks are possibly lost in loss record 4 of 5
= 10352 = at 0x4005903: malloc (vg_replace_malloc.c: 195)
= 10352 = by 0x30DD75: my_once_alloc (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30E59C :??? (In/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30EF96 :??? (In/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30F111: get_charset_by_csname (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x32C3D2: mysql_init_character_set (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x32DABB: mysql_real_connect (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x8048A76: main (str. cpp: 32)
= 10352 =
= 10352 = 28,616 bytes in 7 blocks are possibly lost in loss record 5 of 5
= 10352 = at 0x4005903: malloc (vg_replace_malloc.c: 195)
= 10352 = by 0x30DD75: my_once_alloc (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30E57A :??? (In/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30EF96 :??? (In/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x30F111: get_charset_by_csname (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x32C3D2: mysql_init_character_set (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x32DABB: mysql_real_connect (in/usr/lib/mysql/libmysqlclient. so.15.0.0)
= 10352 = by 0x8048A76: main (str. cpp: 32)
= 10352 =
= 10352 = leak summary:
= 10352 = definitely lost: 0 bytes in 0 blocks
==10352 = indirectly lost: 0 bytes in 0 blocks
==10352 = possibly lost: 53,144 bytes in 13 blocks
= 10352 = still reachable: 8,192 bytes in 3 blocks
= 10352 = suppressed: 0 bytes in 0 blocks
= 10352 = Reachable blocks (those to which a pointer was found) are not shown.
= 10352 = To see them, rerun with: -- leak-check = full -- show-reachable = yes
= 10352 =
= 10352 = For counts of detected and suppressed errors, rerun with:-v
= 10352 = error summary: 2 errors from 2 contexts (suppressed: 3

2. Solutions

Http://dev.mysql.com/doc/refman/5.0/en/mysql-library-end.html

Simply put, it is used after the database is disconnected.

Mysql_library_end ()

Close the database used by MYSQL in mysql_close (...) And then add mysql_library_end ().

Add another sentence. before using the mysql API, you 'd better call mysql_library_init (....)