Compilare: main.cpp: In function 'std::ostream& operator<<(std::ostream&, const SkipList*)': main.cpp:156:5: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp: In function 'int main()': main.cpp:207:25: warning: this 'else' clause does not guard... [-Wmisleading-indentation] else ^~~~ main.cpp:210:29: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'else' if(x==6) ^~