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  1. #include <cstdio>
  2. using namespace std;
  3.  
  4. union myUnion {
  5.     int var1; // 32 bits
  6.     long int var2; // 64 bits
  7.     char var3; // 8 bits
  8. }; // union size is 64 bits (size of largest member)
  9.  
  10. int main()
  11. {
  12.     myUnion a;
  13.     a.var1 = 10;
  14.     printf("a is %ld bits and has value %d\n",sizeof(a)*8,a.var1); // ...has value 10
  15.     a.var2 = 123456789;
  16.     printf("a is %ld bits and has value %ld\n",sizeof(a)*8,a.var2); // ...has value 123456789
  17.     a.var3 = 'y';
  18.     printf("a is %ld bits and has value %c\n",sizeof(a)*8,a.var3); // ...has value y
  19.     printf("a is %ld bits and has value %ld\n",sizeof(a)*8,a.var2); //... has value 123456789, why???
  20.     return 0;
  21. }
Success #stdin #stdout 0s 3468KB
comments (?)
stdin 
Standard input is empty
stdout 
a is 32 bits and has value 10
a is 32 bits and has value 123456789
a is 32 bits and has value y
a is 32 bits and has value 123456889
https://ideone.com/HO5id6
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

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