Compilare: user.cpp: In function ‘int back(int)’: user.cpp:51: warning: no return statement in function returning non-void user.cpp: In function ‘int main()’: user.cpp:56: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:58: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result