Compilare: user.cpp: In function ‘int main()’: user.cpp:28:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spion.in","r",stdin); ^ user.cpp:29:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spion.out","w",stdout); ^ user.cpp:30:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&op); ^ user.cpp:33:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ user.cpp:47:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); ^ user.cpp:49:9: warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false [-Wstrict-overflow] for(i=1;i<=n;i++) ^ /tmp/cc6eK5Bx.o: In function `main': user.cpp:(.text.startup+0x77): warning: the `gets' function is dangerous and should not be used.