Compilare: user.cpp: In function ‘bool eval(std::string)’: user.cpp:26:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<out.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:58:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<s.size()-1;++j) ^ user.cpp:60:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(s[j]=='*') ^