Compilare: user.cpp: In function ‘int main()’: user.cpp:18:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("charlie.in", "r", stdin); ^ user.cpp:19:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("charlie.out", "w", stdout); ^ user.cpp:22:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d\n", &p); ^ user.cpp:24:17: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (s + 1); ^ user.cpp:43:13: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (s); ^ /tmp/ccyRxnPq.o: In function `main': user.cpp:(.text.startup+0x75): warning: the `gets' function is dangerous and should not be used.