Compilare: user.cpp: In function ‘int main()’: user.cpp:9:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.in","r",stdin); ^ user.cpp:10:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.out","w",stdout); ^ user.cpp:12:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:15:26: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir + 1); ^ /tmp/ccmHRnAw.o: In function `main': user.cpp:(.text.startup+0x8c): warning: the `gets' function is dangerous and should not be used.