Compilare: user.cpp: In function 'int eval(std::string)': user.cpp:83: warning: array subscript has type 'char' user.cpp:91: warning: array subscript has type 'char' user.cpp:95: warning: array subscript has type 'char' user.cpp: In function 'int main()': user.cpp:117: warning: array subscript has type 'char' user.cpp:120: warning: array subscript has type 'char' user.cpp:121: warning: array subscript has type 'char' user.cpp:121: warning: array subscript has type 'char'