Compilare: user.cpp: In function ‘int main()’: user.cpp:19: warning: comparison between signed and unsigned integer expressions user.cpp:22: warning: array subscript has type ‘char’ user.cpp:25: warning: array subscript has type ‘char’ user.cpp:32: warning: comparison between signed and unsigned integer expressions user.cpp:34: warning: array subscript has type ‘char’ user.cpp:53: warning: comparison between signed and unsigned integer expressions