Error while doing set_difference: Variable result is not a structure

Question

i had declared a set variable outside a function globally.

std::set s1;
std::set s2;   
std::set interse         


        

Answer 1

This code compiles for me.

Perhaps your compiler is complaining about your underscore usage? Since it says:

Variable result is not a structure.

Whereas you declared _result_.

See What are the rules about using an underscore in a C++ identifier? (as recommended by Mat).

Answer 2

std::set_difference(s1.begin(), s1.end(), s2.begin(), s2.end(),std::inserter(_result_, _result_.end()));

Add type parameter in inserter definition:

std::set_difference(s1.begin(), s1.end(), s2.begin(), s2.end(), std::inserter< std::set<std::string> >(_result_, _result_.end()));