Compilare: user.cpp: In function ‘void build()’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp:36: warning: comparison between signed and unsigned integer expressions user.cpp:41: warning: comparison between signed and unsigned integer expressions user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:107: warning: comparison between signed and unsigned integer expressions user.cpp:115: warning: comparison between signed and unsigned integer expressions