Determination of valid alignment values for C/C + + structures

See such a written question, as follows

The following structure is defined on a 32-bit machine:

struct xx{    longlong  _x1;     Char _x2;     int _x3;     Char _x4[2];     Static int _x5;}; int xx::_x5;

The correct answer is 24.

Did you do the right thing? The following explanations are given:

Determine the effective alignment value of the struct:

1. When not explicitly specified, the length of the longest member in the struct is its valid value
2. When specified with #pragma pack (n), its value is the lesser of the length of the longest member in N and struct.
3. When specifying a length with __attribute__ ((__packed__)), force a valid alignment value for the struct by this value

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Determination of valid alignment values for C/C + + structures