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How to delete stl<map> element from iterator?


After making an iterator to a map and stepping through a loop, I want to
delete any entries that satisfy a test from an external function.

MyMapType::cons t_iterator iter;

for(iter = m->begin(); iter != m->end(); ++iter)
a = iter->first;
b = iter->second;
if ( Test(a,b) == true)

How do I actually delete the element that iter is pointing to?


Feb 21 '06
11 24435
Steve Edwards wrote:
In article <0m************ ****@newsread1. news.pas.earthl ink.net>,
"Mike Wahler" <mk******@mkwah ler.net> wrote:
"Steve Edwards" <gf*@lineone.ne t> wrote in message
news:gf****** *************** **@news.btinter net.com...
How do I actually delete the element that iter is pointing to?

for(iter = m->begin(); iter != m->end(); ++iter)
iter = m->erase(iter);

My compiler is complaining about "iter = m->erase(iter); "

Of course it does. 'm->erase(iter)' returns 'void'. Mike was too hasty
to suggest that solution. It would work for a 'list', for example. It
just doesn't work for 'map'.

Please remove capital As from my address when replying by mail
Feb 21 '06 #11

"Victor Bazarov" <v.********@com Acast.net> wrote in message
news:VJ******** ********@newsre ad1.mlpsca01.us .to.verio.net.. .
Mike Wahler wrote:
"Victor Bazarov" <v.********@com Acast.net> wrote in message
news:mr******** *********@newsr ead1.mlpsca01.u s.to.verio.net. ..
Steve Edwards wrote:
How do I actually delete the element that iter is pointing to?

You ask your map to erase it.

Something like


Beware, though, that after erasing the 'iter' becomes invalid. You
increment it after that. You might want to rewrite your loop like this:

Well, I think we both botched our replies. I forgot the
'else' part, and yours disregards the invalid iterator. :-)

Think again.

OK I did. I see I wasn't thinking before. :-)

for (.... ; ) // no increment at the end
a =
b =
if (..
m->erase(iter++ );

iter = m->erase(iter);

You've already pointed out my error with this line elsethread.

My excuse is ... we've got a new dog, she ate my attention. :-)

Feb 23 '06 #12

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