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John Fly
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 Posted: Wed Sep 14, 2005 7:20 am Post subject: std::<vector> of base class issues.... Why I can't call memb |
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I have a base log class cLog... I'm storeing inhereted "logs" in a
vector of log pointers so I can send generic messages to every log and
have it write out in its own unique format...
Right now to access my member functions I'm having to create a real
pointer, why can't I just use the iterator?
void cLogServer::LogMsg(MessageLevel Level, std::string& Message)
{
std::vector<cLog*>::iterator iLogs = logs_.begin();
std::vector<cLog*>::iterator iLogsEnd = logs_.end();
for(;iLogs != iLogsEnd; iLogs++)
{
cLog* test = *iLogs; <---- Why do I have to use
this
test->Write(INFO, Message);
}
}
I want to use *iLogs->Write(INFO, Message) or something similar.
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Ulrich Eckhardt
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| Posted: Wed Sep 14, 2005 9:45 am Post subject: Re: std::<vector> of base class issues.... Why I can't call |
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John Fly wrote:
| Quote: | std::vector<cLog*>::iterator iLogs = logs_.begin();
cLog* test = *iLogs; <---- Why do I have to use this
I want to use *iLogs->Write(INFO, Message) or something similar.
|
The last snippet is evaluated like this:
*(iLogs->Write(INFO, Message))
but you want
(*iLogs)->Write(INFO, Message)
which is exactly what you should write instead.
Uli
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Tony Delroy
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| Posted: Wed Sep 14, 2005 9:48 am Post subject: Re: std::<vector> of base class issues.... Why I can't call |
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-> has higher precendence than *, so *iLogs->Write(...) tries to
dereference the result of calling the iterator's Write() function. Try
(*iLogs)->Write(...). - Tony
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Ramashish
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| Posted: Wed Sep 14, 2005 9:52 am Post subject: Re: std::<vector> of base class issues.... Why I can't call |
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Hi John,
| Quote: |
Right now to access my member functions I'm having to create a real
pointer, why can't I just use the iterator?
void cLogServer::LogMsg(MessageLevel Level, std::string& Message)
{
std::vector<cLog*>::iterator iLogs = logs_.begin();
std::vector<cLog*>::iterator iLogsEnd = logs_.end();
for(;iLogs != iLogsEnd; iLogs++)
{
cLog* test = *iLogs; <---- Why do I have to use
this
test->Write(INFO, Message);
}
}
I want to use *iLogs->Write(INFO, Message) or something similar.
|
The precedence of -> is higher than *, so you should say
(*iLogs)->Write(INFO, Message);
Regards
Ram
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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Boris Bralo
Guest
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| Posted: Wed Sep 14, 2005 9:53 am Post subject: Re: std::<vector> of base class issues.... Why I can't call |
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Hi john,
| Quote: |
for(;iLogs != iLogsEnd; iLogs++)
{
cLog* test = *iLogs; <---- Why do I have to use
this
test->Write(INFO, Message);
I want to use *iLogs->Write(INFO, Message) or something similar.
Correct statement is: |
(*iLogs)->Write(INFO, Message).
(operator precedence rules).
Boris
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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Bo Persson
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| Posted: Wed Sep 14, 2005 9:53 am Post subject: Re: std::<vector> of base class issues.... Why I can't call |
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"John Fly" <JohnFlyTn (AT) msn (DOT) com> skrev i meddelandet
news:1126635864.859846.107040 (AT) g49g2000cwa (DOT) googlegroups.com...
| Quote: | I have a base log class cLog... I'm storeing inhereted "logs" in a
vector of log pointers so I can send generic messages to every log
and
have it write out in its own unique format...
Right now to access my member functions I'm having to create a real
pointer, why can't I just use the iterator?
void cLogServer::LogMsg(MessageLevel Level, std::string& Message)
{
std::vector<cLog*>::iterator iLogs = logs_.begin();
std::vector<cLog*>::iterator iLogsEnd = logs_.end();
for(;iLogs != iLogsEnd; iLogs++)
{
cLog* test = *iLogs; <---- Why do I have to
use
this
test->Write(INFO, Message);
}
}
I want to use *iLogs->Write(INFO, Message) or something similar.
|
It is a matter of operator precedence. Here operator -> binds before
operator *, so in fact this is equivalent to
*(iLogs->Write(INFO, Message))
which obviously isn't what you want. You should try
(*iLogs)->Write(INFO, Message)
instead.
Bo Persson
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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