C语言中结构和功能内的结构

Question

I've been doing the task of reading data and creating particular structures. In one structure (which contains in itself another structure) eclipse shows "field 'birth' has incomplete type". I've searched through web, but it looks like there is some specific mistake. (Here is shortened version of the code)

typedef struct{
    int birthday_day;
    int birthday_month;
    int birthday_year;
} birthday;

typedef struct{
    int id;
    char name[20];
    struct birthday birth;

}user;

user usser[100];
int i;

for (i=0;i<100;i++){
    fscanf(input, "%s %i %i %i %i", usser[i].id,  
           usser[i].name, usser[i].birth.birthday_day, usser[i].birth.birhday_month,
           usser[i].birth.birthday_year
};

Answer 1

typedef struct _birthday{
    int birthday_day;
    int birthday_month;
    int birthday_year;
} birthday;

typedef struct{
    int id;
    char name[20];
    struct _birthday birth;

}user;

or

typedef struct{
    int id;
    char name[20];
    birthday birth;

}user;

in your example "birthday" is a new type which doesn't need the keyword "struct". That's why you get the error. You can use this type or give a name to the struct and use it with the keyword struct.