Compilare: user.c: In function ‘main’: user.c:6:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ordine.in","r",stdin),freopen("ordine.out","w",stdout),gets(s),n=strlen(s); ^ user.c:6:43: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ordine.in","r",stdin),freopen("ordine.out","w",stdout),gets(s),n=strlen(s); ^ user.c:6:73: warning: ignoring return value of ‘gets’, declared with attribute warn_unused_result [-Wunused-result] freopen("ordine.in","r",stdin),freopen("ordine.out","w",stdout),gets(s),n=strlen(s); ^ /tmp/ccHiuGEj.o: In function `main': user.c:(.text.startup+0x5b): warning: the `gets' function is dangerous and should not be used.