Question

How do you initialize the values of the following struct in a constructor to defined values?

Both options shown in my code example seem to be a bit ugly….

struct T_AnlagenInfo01
{   
    // Option A
    T_AnlagenInfo01() : fReserve80_0(0), fReserve80_1(0),.... {}; 

    // Option B
    T_AnlagenInfo01()
    { 
        memset(this, 0, sizeof(T_AnlagenInfo01));
    } 

    unsigned long fReserve80_0                          : 1;        
    unsigned long fReserve80_1                          : 1;        
    unsigned long fReserve80_2                          : 1;        
    unsigned long fReserve80_3                          : 1;        
    unsigned long fReserve80_4                          : 1;
    unsigned long fReserve80_5                          : 1;
    unsigned long fReserve80_6                          : 1;
    unsigned long fReserve80_7                          : 1;

    unsigned long fReserve81_0                          : 1;        // 81   
    unsigned long fReserve81_1                          : 1;        
    unsigned long fReserve81_2                          : 1;        
    unsigned long fReserve81_3                          : 1;
    unsigned long fReserve81_4                          : 1;
    unsigned long fReserve81_5                          : 1;
    unsigned long fReserve81_6                          : 1;
    unsigned long fReserve81_7                          : 1;
};

Answer 1

One obvious solution would be to put all of the bits in a separate
structure, which is a member of your structure, and copy initialize that
from a static member, e.g.:

struct T_AnlagenInfo01
{
    struct Bits
    {
        unsigned long fReserve80_0 : 1;
        unsigned long fReserve80_1 : 1;
        //  ...
    };
    Bits myBits;
    static Bits initialBits;

    T_AnlagenInfo01 : myBits(initialBits) {}
};

T_AnlagenInfo01::Bits T_AnlagenInfo01::initialBits = {};

This would even allow for certain bits to have a value different from 0.