Re: is it possible to make a map of objects?

From:

Milan Krejci <rdw@no-spam.mail.cz>

Newsgroups:

comp.lang.c++

Date:

Fri, 17 Aug 2007 10:30:50 +0200

Message-ID:

<fa3mbc$2nc3$1@news.vol.cz>

Thanks! now it works only another issue has raised. when i try to list
my map it is executed way too many times for no apparent reason.

    sd=new SD();
     sd->from=first;
     sd->to=last;
     SDoby.insert(std::make_pair(*sd,typ));

    std::map<SD,std::string>::iterator it;
     int a,b; SD s;
    for(it = SDoby.begin(); it != SDoby.end(); it++)
     { s=it->first;
          a=s.vrat_from();
     b=s.vrat_to();
     std::cout << a << " " << it->second << std::endl; //executed way more
times than is supposed to be
     }

Victor Bazarov napsal(a):

Milan Krejci wrote:

Paul napsal(a):

"Milan Krejci" <rdw@no-spam.mail.cz> wrote in message
news:fa1d8c$121c$1@news.vol.cz...

hello, sorry to bother you with this but i can't seem to figure out
why i can't do:

struct SD {
int from;
int to;
} sd;
std::map<sd,std::string> ListOfWorkingSchedule;

First, "sd" is the name of the variable, not the type:
--------------------------------------------------------------------
#include <map>
#include <string>

struct SD {
int from;
int to;
}sd;

std::map<SD, std::string> ListOfWorkingSchedule;

--------------------------------------------------------------------

After this change, you will still get a compiler error, albeit a
different one. Then once you get this new error, try to understand
what it means. If you can't figure it out, post the compiler error
(I know what the problem is -- I'm seeing if you know what the
problem is). Paul

yes, it complains about missing overloaded < operator. i added one but
don't know if correctly
bool operator<(SD const &sd1) {

Since you made it a member, you might want to declare it 'const':

bool operator<(SD const &sd1) const {

if (sd1.from<this.from)

'this' is a pointer. It needs the arrow (->), not the dot (.) to get
to a member. And inside a member function you don't really need to
use 'this' to get to 'from'.

return true;
}

doba.h:11: error: `from' is not a type
doba.h:11: error: request for member of non-aggregate type before ')'
token