What's the bug in the following code?
#include <iostream>
#include <algorithm>
#include <vector>
#include <boost/array.hpp>
#include <boost/bind.hpp>
int ma开发者_如何学编程in() {
boost::array<int, 4> a = {45, 11, 67, 23};
std::vector<int> v(a.begin(), a.end());
std::vector<int> v2;
std::transform(v.begin(), v.end(), v2.begin(),
boost::bind(std::multiplies<int>(), _1, 2));
std::copy(v2.begin(), v2.end(), std::ostream_iterator<int>(std::cout, " "));
}
When run, this gives a creepy segmentation fault. Please tell me where I'm going wrong.
v2
has a size of zero when you call transform
. You either need to resize v2
so that it has at least as many elements as v
before the call to transform
:
v2.resize(v.size());
or you can use std::back_inserter
in the call to transform
:
std::transform(v.begin(), v.end(), std::back_inserter(v2), boost::bind(std::multiplies<int>(), _1, 2));
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