Compilare: user.c: In function ‘main’: user.c:11:10: warning: variable ‘smen’ set but not used [-Wunused-but-set-variable] char ch, smen; ^ user.c:9:8: warning: unused variable ‘a’ [-Wunused-variable] int i, a, b = 0; ^ user.c:8:15: warning: variable ‘file2’ set but not used [-Wunused-but-set-variable] FILE *file1, *file2; ^ user.c:8:7: warning: variable ‘file1’ set but not used [-Wunused-but-set-variable] FILE *file1, *file2; ^ user.c:16:6: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &length); ^