How to initialize an int buried 2 levels deep inside typdef'd unions

Question

I would like to perform the following

static Type2 MyData;
MyData.Base.Data = (0b0000000000010100);

as a static initialization. For example

static Type2 MyData = (typecast)(0b0000000000010100);

What would I typecast this with? Here are the typedefs for Type1 and Type2

typedef union
{
    UINT16 Data;
    struct
    {
        unsigned      :10;  
        unsigned var1 :3;   
        unsigned var2 :2;   
        unsigned var3 :1;   
    };
} Type1;    

typedef union
{
    Type1 Base;     
    struct
    {
        unsigned var4 :3;
        unsigned var5 :2;   
        unsigned      :11;
    } Data;
} Type2;

Why do you need to do this with a cast? Can't you do it within the type system? — David Heffernan, Mar 05 '12 at 18:54
I get an invalid initialization error. the compiler cannot automatically cast from scalar to non scalar types — Jeremy, Mar 05 '12 at 19:06
No, what I mean is that you don't cast at all. Use standard struct/union initialization syntax to initialize memberwise. — David Heffernan, Mar 05 '12 at 19:11

score 1 · Accepted Answer · edited May 23 '17 at 11:55

1

Similar to this question, try Type2 t = { .Base.Data = 0x18 }; If your goal is to set the bitfields in Type1 you should probably call them out directly; see here.

edited May 23 '17 at 11:55

Community

1
1

answered Mar 05 '12 at 19:07

Matt K

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How to initialize an int buried 2 levels deep inside typdef'd unions

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