Question

I would like to perform the same operation on several arrays, something like:

#include<vector>
#include<algorithm>
int main(void){
    std::vector<double> a, b;
    for(auto& ab:{a,b}) std::sort(ab.begin(),ab.end()); // error 
}

This code fails, since auto& is a const-reference. Is there an elegant way around it?

Answer 1

I think the issue is that it’s a bit like binding a temporary to a non-const reference. There is no “concrete” collection there so it is a bit like a temporary.

IF you have a temporary vector there, it will bind to a const reference but not a non-const one.

I also think this won’t ever work what you are doing, but this should work:

#include<vector> 
#include<algorithm> 
int main(void)
{     
    std::vector<double> a, b;     
    for(std::vector<double>* ab:{&a,&b}) 
      std::sort(ab->begin(),ab->end()); // or begin(*ab),end(*ab)
} 

and auto may work too.