How to copy the data from a struct/union variable

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January 10th, 2013, 10:24 PM

asdk77

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How to copy the data from a struct/union variable

Code:

struct A
 {
    union 
    {
      struct B
      {}b;
      struct C
      {}c;
      struct D
      {}d;
    }e;
 
   struct F
    {}f;
    ....
 }a;
 A b;

I want to copy the data of a to b, or just the union part of a to b. There two ways:
(1) b = a; b.e = a.e;
(2) memcpy(&b,&a, sizeof(a)); memcpy(&b.e,&a.e, sizeof(a.e));
I am confused and not sure which method is correct.
I hope someone can explain.
Thanks!

January 11th, 2013, 12:49 AM

salem

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> (1) b = a; b.e = a.e;
Since this actually works, I'd go with this approach.

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