agendatelefonica.cpp: In function `int count(int, char*)': agendatelefonica.cpp:13: warning: NULL used in arithmetic agendatelefonica.cpp:15: warning: comparison between signed and unsigned integer expressions agendatelefonica.cpp: In function `void insert(int, char*)': agendatelefonica.cpp:23: warning: NULL used in arithmetic agendatelefonica.cpp:25: warning: comparison between signed and unsigned integer expressions