Compilare: user.cpp: In function ‘bool get_and(std::string)’: user.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() && s[i]=='&') ^ user.cpp: In function ‘bool get_xor(std::string)’: user.cpp:64:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() && s[i]=='^') ^ user.cpp: In function ‘bool eval(std::string)’: user.cpp:74:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<s.size() && s[i]=='|') ^ user.cpp: In function ‘int main()’: user.cpp:90:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s1.size();++i) ^ user.cpp:99:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s2.size();++i){ ^ user.cpp:117:34: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] for(int per=0;per<(1<<cnt+1) && !okk;++per) ^