Eroare de compilare: user.c: In function ‘main’: user.c:27:5: warning: implicit declaration of function ‘strrev’ [-Wimplicit-function-declaration] printf("%s",s);strrev(s); ^ user.c:23:13: warning: unused variable ‘j’ [-Wunused-variable] int i , j; ^ user.c:19:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(in, "r", stdin); ^ user.c:20:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(out, "w", stdout); ^ user.c:21:9: warning: ignoring return value of ‘gets’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/cc1ZJYoo.o: In function `main': user.c:(.text.startup+0x55): warning: the `gets' function is dangerous and should not be used. user.c:(.text.startup+0x104): undefined reference to `strrev' collect2: error: ld returned 1 exit status