Compilare: user.cpp: In function ‘bool cmp(std::string, std::string)’: user.cpp:10:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=a.length(); i<b.length(); i++) ^ user.cpp:12:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=b.length(); i<a.length(); i++) ^ user.cpp:14:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a.length(); i++) ^ user.cpp:15:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (fq[a[i]]<fq[b[i]]) return 1; else if (fq[a[i]]>fq[b[i]]) return 0; ^ user.cpp:15:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (fq[a[i]]<fq[b[i]]) return 1; else if (fq[a[i]]>fq[b[i]]) return 0; ^ user.cpp:15:58: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (fq[a[i]]<fq[b[i]]) return 1; else if (fq[a[i]]>fq[b[i]]) return 0; ^ user.cpp:15:67: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (fq[a[i]]<fq[b[i]]) return 1; else if (fq[a[i]]>fq[b[i]]) return 0; ^ user.cpp: In function ‘int main()’: user.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<s.length(); i++) fq[s[i]]=i+1; ^ user.cpp:25:41: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (i=0; i<s.length(); i++) fq[s[i]]=i+1; ^ user.cpp: In function ‘bool cmp(std::string, std::string)’: user.cpp:16:1: warning: control reaches end of non-void function [-Wreturn-type] } ^