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:90:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<max(s1.size(),s2.size());++i) ^ user.cpp:92:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<s1.size() && isalpha(s1[i]) && !fol1[s1[i]] && !fol2[s1[i]]) ^ user.cpp:98:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(i< s1.size() && isalpha(s1[i]) && !fol1[s1[i]]) ^ user.cpp:100:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i<s2.size() && isalpha(s2[i]) && !fol2[s2[i]] && !fol1[s2[i]]) ^ user.cpp:106:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(i< s2.size() && isalpha(s2[i]) && !fol2[s2[i]]) ^ user.cpp:112:34: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] for(int per=0;per<(1<<cnt+1) && !okk;++per) ^