Compilare: user.cpp: In function ‘void Do()’: user.cpp:39:41: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ((s[i]==')' && s[d.back()]=='(') || (s[i]==']' && s[d.back()]=='[') || (s[i]=='}' && s[d.back()]=='{')) ^ user.cpp:39:76: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ((s[i]==')' && s[d.back()]=='(') || (s[i]==']' && s[d.back()]=='[') || (s[i]=='}' && s[d.back()]=='{')) ^ user.cpp:39:111: warning: array subscript has type ‘char’ [-Wchar-subscripts] if ((s[i]==')' && s[d.back()]=='(') || (s[i]==']' && s[d.back()]=='[') || (s[i]=='}' && s[d.back()]=='{')) ^ user.cpp:41:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] a[d.back()]=1; ^ user.cpp:38:13: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] { if(!d.empty()) ^ user.cpp: In function ‘char Complement(char)’: user.cpp:20:1: warning: control reaches end of non-void function [-Wreturn-type] } ^