Compilare: user.cpp: In function ‘void solve()’: user.cpp:50:60: warning: array subscript has type ‘char’ [-Wchar-subscripts] operands[++numberOfOperands] = characters[value]; ^ user.cpp:57:166: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (numberOfOperands != 0 && numberOfOperators != 0 && operators[numberOfOperators] != '(' && priority[operators[numberOfOperators]] >= priority[value]) { ^ user.cpp: In function ‘int main()’: user.cpp:72:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] characters[c] = !characters[c]; ^ user.cpp:72:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] characters[c] = !characters[c]; ^