Compilare: user.cpp: In function ‘void read()’: user.cpp:12:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gbc.in", "r", stdin); ^ user.cpp:13:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n", &k, &n, &m); ^ user.cpp:16:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp: In function ‘void write()’: user.cpp:75:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gbc.out", "w", stdout); ^ /tmp/ccviUfo5.o: In function `read()': user.cpp:(.text+0x68): warning: the `gets' function is dangerous and should not be used.