Borderou de evaluare (job #263078)

Compilare: user.cpp: In function ‘void back(int)’: user.cpp:29:16: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] user.cpp:37:16: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] user.cpp:45:16: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] user.cpp: In function ‘int main()’: user.cpp:51:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:52:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:53:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:54:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]