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copied!<p>Boost lambda will evaluate <code>rand</code> before the functor is made. You need to <code>bind</code> it, so it's evaluated at lambda evaluation time:</p> <pre><code>#include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> // for bind #include <algorithm> #include <cstdlib> #include <ctime> #include <iostream> #include <vector> int main() { namespace bl = boost::lambda; typedef std::vector<int> int_vec; static const size_t MaxListSize = 10; static const int MaxSize = 20; int_vec theList; theList.resize(MaxListSize); std::srand(static_cast<unsigned>(std::time(0))); std::for_each(theList.begin(), theList.end(), bl::_1 = bl::bind(std::rand) % MaxSize); std::for_each(theList.begin(), theList.end(), std::cout << bl::_1 << ' ' ); } </code></pre> <p>This works as expected.</p> <p>However, the <em>correct</em> solution is to use <code>generate_n</code>. Why make a bunch of 0's just to overwrite them?</p> <pre><code>#include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> #include <algorithm> #include <cstdlib> #include <ctime> #include <iostream> #include <vector> int main() { namespace bl = boost::lambda; typedef std::vector<int> int_vec; static const size_t MaxListSize = 10; static const int MaxSize = 20; int_vec theList; theList.reserve(MaxListSize); // note, reserve std::srand(static_cast<unsigned>(std::time(0))); std::generate_n(std::back_inserter(theList), MaxListSize, bl::bind(std::rand) % MaxSize); std::for_each(theList.begin(), theList.end(), std::cout << bl::_1 << ' ' ); } </code></pre>

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