Eroare de compilare: user.c: In function ‘main’: user.c:20:9: error: ‘len’ undeclared (first use in this function) len=strlen(v); ^ user.c:20:9: note: each undeclared identifier is reported only once for each function it appears in user.c:13:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("joben.in","r",stdin); ^ user.c:14:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("joben.out","w",stdout); ^ user.c:16:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.c:19:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",v); ^ user.c:25:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",v); ^