C ++ struct containing unsigned char and int bug

Question

Ok, I have a structure in my C ++ program that looks like this:

struct thestruct
{
 unsigned char var1;
 unsigned char var2;
 unsigned char var3[2];
 unsigned char var4;
 unsigned char var5[8];
 int var6;
 unsigned char var7[4];
};

When I use this structure, 3 random bytes are added to "var6", if I delete "var5", it is still before "var6", so I always know this before "var6".

But if I delete "var6", then 3 extra bytes will disappear.

If I use only the construct with int in it, there are no extra bytes.

So there is a conflict between unsigned char and int, how can I fix this?

Answer 1

, , , x , x.

, #pragma, :

#pragma pack(1)

Visual ++:

, . n 8. : 1, 2, 4, 8 16. , n , , .

, , . , (, Intel x86) ( ).

Answer 2

, int , 32 64 .
, :

struct thestruct
{
 int var6;
 unsigned char var1;
 unsigned char var2;
 unsigned char var3[2];
 unsigned char var4;
 unsigned char var5[8];
 unsigned char var7[4];
};

Answer 3

? . ++, , aligned. .

Answer 4

. . .

Answer 5

. , -2.

, (int ) ( char) , .

Answer 6

, struct, , , #pragma .. , . , , , undefined.