Re: extracting data from std::set<string>

From:
Rui Maciel <rui.maciel@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 19 Oct 2012 16:19:13 +0100
Message-ID:
<k5rr1e$108$1@speranza.aioe.org>
Rene Ivon Shamberger wrote:

I am trying to extract data from a set container, but to no avail. This is
what I have done. int main(){
std::set<const std::string> data;
data.insert("one");
data.insert("two");
data.insert("three");
int counter = 0;

std::set<std::string>::iterator it;
for (it = data.begin(); it != data.end(); it++) {
counter++;
std::cout << *it;
}
return 0;
}


here's your problem:

std::set<const std::string> data;


The STL allocates objects using C++'s allocators, which only store non-
const, non-reference object types. You are trying to allocate a const-
object type. Hence, the flood of compiler errors you should be getting from
this.

Replace the above with:

    std::set<std::string> data;

and everything will work fine.

While you are at it, use const iterators to enforce the object's const-ness.
So, replace:

std::set<std::string>::iterator it;


with

    std::set<std::string>::const_iterator it;

Hope this helps,
Rui Maciel

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