Compilare: user.cpp: In function ‘std::string parse(std::string)’: user.cpp:15:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i<s.length()) { ^ user.cpp:19:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i<s.length()-2 && s[i]=='A' && s[i+1]=='N' && s[i+2]=='D') { result+='a'; i+=3; } ^ user.cpp:20:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i<s.length()-2 && s[i]=='N' && s[i+1]=='O' && s[i+2]=='T') { result+='n'; i+=3; } ^ user.cpp:21:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i<s.length()-1 && s[i]=='O' && s[i+1]=='R') { result+='o'; i+=2; } ^ user.cpp:22:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i<s.length()-3 && s[i]=='T' && s[i+1]=='R' && s[i+2]=='U' && s[i+3]=='E') { result+='t'; i+=4; } ^ user.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i<s.length()-3 && s[i]=='F' && s[i+1]=='A' && s[i+2]=='L' && s[i+3]=='S') { result+='f'; i+=5; } ^ user.cpp: In function ‘bool evalNot()’: user.cpp:49:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] return aux[s[l-1]]; ^ user.cpp: In function ‘int main()’: user.cpp:93:9: warning: array subscript has type ‘char’ [-Wchar-subscripts] aux[ch]=1-aux[ch]; ^ user.cpp:93:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] aux[ch]=1-aux[ch]; ^