State the difference between structure and union with suitable example in C language

The differences between structures and unions in C language are explained below −

S.No	Structure	Union
1	Definition Structure is heterogenous collection of data items grouped together under a single name	Definition A union is a memory location that is shared by several variables of different datatypes.
2	Syntax; struct tagname{    datatype member1;    datatype member2;    ----    ----    ---- };	Syntax; union tagname{    datatype member1;    datatype member2;    ----    ----    ---- };
3	Eg; struct sample{    int a;    float b;    char c; };	Eg; union sample{    int a;    float b;    char c; };
4	keyword − struct	keyword − union
5	Memory allocation	Memory allocation
6
7	Memory allocated is the sum of sizes of all datatypes in structure(Here, 7bytes)	Memory allocated is the maximum size allocated among all the datatypes in union(Here, 4bytes)
8	Memory is allocated for all the members of the structure differently	Only one member will be residing in the memory at any particular instance

Example

Following is the C program for structures −

#include<stdio.h>
struct size{
   double a;
   int b;
   char c;
   float d;
};
int main(){
   printf("%ld",sizeof( stuct size));
}

Output

When the above program is executed, it produces the following result −

24

Example

Following is the C program on union −

#include<stdio.h>
union size{
   double a;
   int b;
   char c;
   float d;
}
Int main(){
   Printf("ld",sizeof(union size));
}

Output

When the above program is executed, it produces the following result −

8

Bhanu Priya

Updated on: 09-Mar-2021

1K+ Views

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