Compilare: user.cpp: In function ‘bool higherPrecedence(char, char)’: user.cpp:37:7: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(wop1==wop2) ^ user.cpp: In function ‘std::string postfix(std::string)’: user.cpp:47:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<expr.length(); ++i) ^ user.cpp: In function ‘long long int evaluate(std::string)’: user.cpp:103:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.length(); ++i) ^