Compilare: user.cpp: In function ‘void makeprefix()’: user.cpp:10:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 2; i < A.length(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < B.length(); i++) ^ user.cpp:34:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == A.length() - 1) ^