Compilare: user.cpp: In function ‘int main()’: user.cpp:18: warning: comparison between signed and unsigned integer expressions user.cpp:20: warning: array subscript has type ‘char’ user.cpp:23: warning: comparison between signed and unsigned integer expressions user.cpp:25: warning: array subscript has type ‘char’ user.cpp:31: warning: comparison between signed and unsigned integer expressions user.cpp:45: warning: array subscript has type ‘char’