Compilare: user.cpp: In function ‘int cmp(const nod&, const nod&)’: user.cpp:40:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ( pos[ x.sir[i] ] != pos[ y.sir[i] ] ) ^ user.cpp:40:47: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ( pos[ x.sir[i] ] != pos[ y.sir[i] ] ) ^ user.cpp:41:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] return pos[ x.sir[i] ] < pos[ y.sir[i] ]; ^ user.cpp:41:56: warning: array subscript has type ‘char’ [-Wchar-subscripts] return pos[ x.sir[i] ] < pos[ y.sir[i] ]; ^ user.cpp: In function ‘int main()’: user.cpp:60:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 0; i < sir.size(); ++i ) ^ user.cpp:61:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] pos[ sir[i] ] = i; ^