(C++) std::negate

 

std::negate is an STL functor for negation of values: it changes x to -x (and -x to x).

 

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#include <algorithm> #include <cassert> #include <functional> #include <vector> int main() {   //Create an initial std::vector   std::vector<int> v;   v.push_back(0);   v.push_back(1);   v.push_back(2);   v.push_back(3);   //Create another std::vector   std::vector<int> w;   //Append the negated values from v to w   std::transform(v.begin(),v.end(),std::back_inserter(w),std::negate<int>());   //Check if std::negate worked properly   assert(v.size() == w.size());   assert(v[0] == - w[0]);   assert(v[1] == - w[1]);   assert(v[2] == - w[2]);   assert(v[3] == - w[3]); }