I have a code in C++14. However, when I used it in C++11, it has an error at const auto
. How to use it in C++11?
vector<vector <int> > P;
std::vector<double> f;
vector< pair<double, vector<int> > > X;
for (int i=0;i<N;i++)
X.push_back(make_pair(f[i],P[i]));
////Sorting fitness descending order
stable_sort(X.rbegin(), X.rend());
std::stable_sort(X.rbegin(), X.rend(),
[](const auto&lhs, const auto& rhs) { return lhs.first < rhs.first; });
Best Answer
C++11 doesn't support generic lambdas. That's what
auto
in the lambda's parameter list actually stands for: a generic parameter, comparable to parameters in a function template. (Note that theconst
isn't the problem here.)You have basically two options:
Type out the correct type instead of
auto
. Here it is the element type ofX
, which ispair<double, vector<int>>
. If you find this unreadable, a typedef can help.Replace the lambda with a functor which has a call operator template. That's how generic lambdas are basically implemented behind the scene. The lambda is very generic, so consider putting it in some global utility header. (However do not
using namespace std;
but type outstd::
in case you put it in a header.)