list::sort with pointers

[Tim Partridge]

How do I define the use of list::sort() when the list holds pointers? For
example,

#include <list>

class foo {
public:
foo(int i): i(i) {};
~foo();

private:
int i;
};

void main() {
foo *f = new foo(3);
foo *g = new foo(2);

list< foo* > l;
l.push_back(f);
l.push_back(g);

l.sort(); // I want this to sort based on foo::i
}


Thanks,
Tim Partridge

[Socketd]

Re: list::sort with pointers

On Wed, 13 Aug 2003 12:35:27 -0400
Tim Partridge <tjpartri@lassa r.math.uwaterlo o.ca> wrote:
[color=blue]
> How do I define the use of list::sort() when the list holds pointers?
> For example,
>
> #include <list>
>
> class foo {
> public:
> foo(int i): i(i) {};
> ~foo();
>
> private:
> int i;
> };
>
> void main() {
> foo *f = new foo(3);
> foo *g = new foo(2);
>
> list< foo* > l;
> l.push_back(f);
> l.push_back(g);
>
> l.sort(); // I want this to sort based on foo::i
> }[/color]

You can't call sort on a list with pointers. You have to specify a
sorting function: l.sort(someFunc tion);

br
socketd

[John Harrison]

Re: list::sort with pointers


"Tim Partridge" <tjpartri@lassa r.math.uwaterlo o.ca> wrote in message
news:Pine.SOL.4 .44.03081312243 60.5826-100000@lassar.m ath.uwaterloo.c a...[color=blue]
> How do I define the use of list::sort() when the list holds pointers? For
> example,
>
> #include <list>
>
> class foo {
> public:
> foo(int i): i(i) {};
> ~foo();
>
> private:
> int i;
> };
>
> void main() {
> foo *f = new foo(3);
> foo *g = new foo(2);
>
> list< foo* > l;
> l.push_back(f);
> l.push_back(g);
>
> l.sort(); // I want this to sort based on foo::i
> }
>
>
> Thanks,
> Tim Partridge
>[/color]

bool sort_func(foo* lhs, foo* rhs)
{
return lhs->i < rhs->i;
}

l.sort(sort_fun c);

Aside from the fact that i is private, that should work, but untested code.

john