Question

How to use union in C++

Answer 1

#include <iostream>
#include <cstring>

union un {      
  	int a;
  	char s[20];
  	float f;
};


int main()
{
	union un u;
	
	std::cout << "size: " << sizeof(un) << "\n";
	
	u.a = 546;
	std::cout << u.a  << "\n";
	std::cout << "size: " << sizeof(un) << "\n";
	
	strcpy(u.s, "C++");
	std::cout << u.s  << "\n";
	std::cout << "size: " << sizeof(un) << "\n";
	
	u.f = 3.14;
	std::cout << u.f  << "\n";
	std::cout << "size: " << sizeof(un) << "\n";
	
	return 0;
}
   
   
   
/*
run:
   
size: 20
546
size: 20
C++
size: 20
3.14
size: 20
   
*/

 

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