1 #include <stdio.h> 2  3 struct struct_a 4 { 5     int a; 6     int b; 7 }; 8  9 enum Weekday10 {11     Mon,12     Tue,13     sat,14     sun15 };16 17 union bigend18 {19     int a;20     char c;21 };22 23 int main()24 {25     struct_a sa;26     sa.b = 2;27     sa.a = 1;28     29     printf("struct %d\n",sa.b);30     31     Weekday wd;32     wd = sun;33     34     printf("enum %d\n", wd);35     36     bigend be;37     be.a = 97;38     39     printf("union %c\n",be.c);40     return 0;41 }