Compilare: user.cpp: In function ‘void read()’: user.cpp:21: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int ins(int, int)’: user.cpp:37: warning: no return statement in function returning non-void user.cpp: In function ‘void df(int, int)’: user.cpp:44: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:81: warning: comparison between signed and unsigned integer expressions user.cpp:82: warning: comparison between signed and unsigned integer expressions