Compilare: user.cpp: In function 'bool isoperand(std::string)': user.cpp:12: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'std::string goahead(std::string&)': user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp:36: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'long long int minieval(char, long long int, long long int)': user.cpp:111: warning: control reaches end of non-void function user.cpp: In function 'int priority(char)': user.cpp:58: warning: control reaches end of non-void function