Nested Structure in C

Nested structure in c language can have another structure as a member. There are two ways to define nested structure in c language:

1. By separate structure
2. By Embedded structure

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1) Separate structure

We can create 2 structures, but dependent structure should be used inside the main structure as a member. Let's see the code of nested structure.

1. struct Date  
2. {  
3.    int dd;  
4.    int mm;  
5.    int yyyy;   
6. };  
7. struct Employee  
8. {     
9.    int id;  
10.    char name[20];  
11.    struct Date doj;  
12. }emp1;  

As you can see, doj (date of joining) is the variable of type Date. Here doj is used as a member in Employee structure. In this way, we can use Date structure in many structures.

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2) Embedded structure

We can define structure within the structure also. It requires less code than previous way. But it can't be used in many structures.

1. struct Employee  
2. {     
3.    int id;  
4.    char name[20];  
5.    struct Date  
6.     {  
7.       int dd;  
8.       int mm;  
9.       int yyyy;   
10.     }doj;  
11. }emp1;  

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Accessing Nested Structure

We can access the member of nested structure by Outer_Structure.Nested_Structure.member as given below:

1. e1.doj.dd  
2. e1.doj.mm  
3. e1.doj.yyyy  

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C Nested Structure example

Let's see a simple example of nested structure in C language.

1. #include <stdio.h>  
2. #include <string.h>  
3. struct Employee  
4. {     
5.    int id;  
6.    char name[20];  
7.    struct Date  
8.     {  
9.       int dd;  
10.       int mm;  
11.       int yyyy;   
12.     }doj;  
13. }e1;  
14. int main( )  
15. {  
16.    //storing employee information  
17.    e1.id=101;  
18.    strcpy(e1.name, "Sonoo Jaiswal");//copying string into char array  
19.    e1.doj.dd=10;  
20.    e1.doj.mm=11;  
21.    e1.doj.yyyy=2014;  
22.   
23.    //printing first employee information  
24.    printf( "employee id : %d\n", e1.id);  
25.    printf( "employee name : %s\n", e1.name);  
26.    printf( "employee date of joining (dd/mm/yyyy) : %d/%d/%d\n", e1.doj.dd,e1.doj.mm,e1.doj.yyyy);  
27.    return 0;  
28. }  

Output:

employee id : 101

employee name : Sonoo Jaiswal

employee date of joining (dd/mm/yyyy) : 10/11/2014