Use union to share memory between members - C Data Type

C examples for Data Type:union

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Introduction

structures reserve separate memory segments for each member, a union reserves a single memory space for its largest member.

Unions are created with the keyword union.

The following code creates a union definition for a phone book. 

union phoneBook { 
   char *name; 
   char *number; 
   char *address; 
};

union members are accessed via the dot operator.

Demo Code

#include <stdio.h> 
union phoneBook { 
   char *name;  /*from   w  w w .j  a v  a 2s  .  c o m*/
   char *number; 
   char *address; 
}; 

struct magazine { 
   char *name; 
   char *author; 
   int isbn; 
}; 

int main()
{ 
   union phoneBook aBook; 
   struct magazine aMagazine; 
   printf("\nUnion Details\n"); 
   printf("Address for aBook.name: %p\n", &aBook.name); 
   printf("Address for aBook.number: %p\n", &aBook.number); 
   printf("Address for aBook.address: %p\n", &aBook.address); 
   printf("\nStructure Details\n"); 
   printf("Address for aMagazine.name: %p\n", &aMagazine.name); 
   printf("Address for aMagazine.author: %p\n", &aMagazine.author); 
   printf("Address for aMagazine.isbn: %p\n", &aMagazine.isbn); 
} //end main

Result


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