RE: [Dev-C++] STL Map question

[Ioannis V. <iv...@em...>]

-----Original Message-----
From: dev...@li...
[mailto:dev...@li...] On Behalf Of Shane =
Bryldt
Sent: Thursday, July 10, 2003 12:54 AM
To: C++
Subject: [Dev-C++] STL Map question



Hello,
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    I recently ran into an issue that I can't seem to pinpoint the cause =
of.
99% of the time, it seems to work, so it seems to be a small situational
bug.  Subject, is a UserList class, which internally implements an STL =
map.
I am not sure why, but it seems to crash occasionally when I attempt to =
call
the map::find function, with a valid null terminated char array.  The =
map
template implements a simple case insensative comparison.  As I said, it
works more often than not, but for some reason when attempting to delete
from the list sometimes, it causes a SEGFAULT.  Here is what GDB has to =
say:
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Program received signal SIGSEGV, Segmentation fault.
0x80bb142 in _Rb_tree<char const *, pair<char const *const, User *>,
_Select1st<pair<char const *const, User *> >, UserList::ltstr,
allocator<User *> >::find (
    this=3D0xbf14b30, __k=3D@0xbfbff7bc) at =
/usr/include/g++/stl_tree.h:1118
1118      _Link_type __x =3D _M_root();      // Current node.=20
(gdb) up
#1  0x80bb529 in map<char const *, User *, UserList::ltstr, =
allocator<User
*> >::find (this=3D0xbf14b30, __x=3D@0xbfbff7bc) at
/usr/include/g++/stl_map.h:187
187       iterator find(const key_type& __x) { return _M_t.find(__x); }
(gdb) up
#2  0x80ba8e9 in UserList::DeleteUser (this=3D0xbf14b30,=20
    pNick=3D0xbf12300 "_=C7=E1=DF=D1=D2_") at UserList.cpp:26
26              UserMap::iterator it =3D m_mapUsers.find(pNick);
(gdb) print pNick
$1 =3D 0xbf12300 "_=C7=E1=DF=D1=D2_"
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And here is the code in question.
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bool UserList::DeleteUser(const char *pNick)
{
    bool bRet =3D false;
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    if(m_mapUsers.size() > 0)
    {
        UserMap::iterator it =3D m_mapUsers.find(pNick);
        if(it !=3D m_mapUsers.end())
        {
            m_mapUsers.erase(it);
            bRet =3D true;
        }
    }
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    return bRet;
}

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My first thought was that the MAP container had issues when attempting =
to
"find" with 0 elements, but that didn't seem to affect anything.  Any
thoughts?=20

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Are you sure that m_mapUsers is an object of type UserMap and UserMap is =
a
typedef of a map type?
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Ioannis Vranos

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<http://www.noicys.freeurl.com/>=20
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<http://www.noicys.cjb.net/>


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